Sandisk ultra 240gb ssd review: SanDisk Ultra II (240GB) SSD Review

SanDisk Ultra II (240GB) SSD Review

Two years ago Samsung dropped the bomb by releasing the first TLC NAND based SSD. I still vividly remember Anand’s reaction when I told him about the SSD 840. I was in Korea for the launch event and was sitting in a press room where Samsung held the announcement. Samsung had only sampled us and everyone else with the 840 Pro, so the 840 and its guts had remained as a mystery. As soon as Samsung lifted the curtain on the 840 specs, I shot Anand a message telling him that it was TLC NAND based. The reason why I still remember this so clearly is because I had to tell Anand three times that, «Yes, I am absolutely sure and am not kidding» before he took my word.

For nearly two years Samsung was the only manufacturer with an SSD that utilized TLC NAND. Most of the other manufacturers have talked about TLC SSDs in one way or another, but nobody has come up with anything retail worthy… until now. A month ago SanDisk took the stage and unveiled their Ultra II, the company’s first TLC SSD and the first TLC SSD that is not by Samsung. Obviously, there’s a lot to discuss, but let’s start with a quick overview of TLC and the market landscape.

There are a variety of reasons for Samsung’s head start in the TLC game. Samsung is the only client SSD manufacturer with a fully integrated business model: everything inside Samsung SSDs is designed and manufactured by Samsung. That is unique in the industry because even though the likes of SanDisk and Micron/Crucial manufacture NAND and develop their own custom firmware, they rely on Marvell’s controllers for their client drives. Third party silicon always creates some limitations because it is designed based on the needs of several customers, whereas in-house silicon can be designed for a specific application and firmware architecture.

Furthermore, Samsung is the only NAND manufacturer in addition to SK Hynix that is not in a NAND joint-venture. Without a partner Samsung has the full freedom to dedicate as much (or as little) resources and fab space to TLC development and production as necessary, while SanDisk must coordinate with Toshiba to ensure that both companies are satisfied with the development and production strategy.

From what I have heard, the two major problems with TLC have been late production ramp up and low volume. In other words, it has taken two or three additional quarters for TLC NAND to become mature enough for SSDs compared to MLC NAND at the same node, which means that a new MLC node is already sampling and will be available for SSD use within a couple of quarters. It has simply made sense to wait for the smaller and more cost efficent MLC node to become available instead of focusing development resources on a TLC SSD that would become obsolete in a matter of months.

SanDisk and Toshiba seem to have revised their strategy, though, because their second generation 19nm TLC is already SSD-grade and the production of both MLC and TLC flavors of the 15nm node are ramping up as we speak. Maybe TLC is finally becoming a first class citizen in the fab world. Today’s review will help tell us more about the state of TLC NAND outside of Samsung’s world. I am not going to cover the technical aspects of TLC here because we have done that several times before, so take a look at the links in case you need a refresh on how TLC works and how it differs from SLC/MLC.

The Ultra II is available in four capacities: 120GB, 240GB, 480GB and 960GB. The 120GB and 240GB models are shipping already, but the larger 480GB and 960GB models will be available in about a month. All come in a 2.5″ 7mm form factor with a 9.5mm spacer included. There are no mSATA or M.2 models available and from what I was told there are not any in the pipeline either (at least for retail). SanDisk has always been rather conservative with their retail lineup and they have not been interested in the small niches that mSATA and M.2 currently offer, so it is logical decision to stick with 2.5″ for now.

SanDisk Ultra II Specifications
Capacity 120GB 240GB 480GB 960GB
Controller Marvell 88SS9190 Marvell 88SS9189
NAND SanDisk 2nd Gen 128Gbit 19nm TLC
Sequential Read 550MB/s 550MB/s 550MB/s 550MB/s
Sequential Write 500MB/s 500MB/s 500MB/s 500MB/s
4KB Random Read 81K IOPS 91K IOPS 98K IOPS 99K IOPS
4KB Random Write 80K IOPS 83K IOPS 83K IOPS 83K IOPS
Idle Power (Slumber) 75mW 75mW 85mW 85mW
Max Power (Read/Write) 2. 5W / 3.3W 2.7W / 4.5W 2.7W / 4.5W 2.9W / 4.6W
Encryption N/A
Warranty Three years
Retail Pricing $80 $112 $200 $500

There are two different controller configurations: the 120GB and 240GB models are using the 4-channel 9190 «Renoir Lite» controller, whereas the higher capacity models use the full 8-channel design 9189 «Renoir» silicon. To my knowledge there is not any difference besides the channel count (perhaps in internal cache sizes too), and the «Lite» version is cheaper. SanDisk has done this before with the X300s for instance, so having two different controllers is not really anything new and it makes sense because the smaller capacities cannot take full advantage of all eight channels anyway. Note that the 9189/9190 is not the new TLC-optimized 1074 controller from Marvell – it is the same controller that is used in Crucial’s MX100 for example.

Similar to the rest of SanDisk’s client SSD lineup, the Ultra II does not offer any encryption support. For now SanDisk is only offering encryption in the X300s, but in the future TCG Opal 2.0 and eDrive support will very likely make their way to the client drives as well. DevSleep is not supported either and SanDisk said the reason is that the niche for aftermarket DevSleep-enabled SSDs is practically non-existent. Nearly all platforms that support DevSleep (which is very few, actually) already come with SSDs, e.g. laptops, so DevSleep is not a feature that buyers find valuable.

nCache 2.0

The Ultra II offers rather impressive performance numbers for a TLC drive as even the smallest 120GB model is capable of 550MB/s read and 500MB/s write. The secret behind the performance is the new nCache 2.0, which takes SanDisk’s pseudo-SLC caching mode to a next level. While the original nCache was mainly designed for caching the NAND mapping table along with some small writes (<4KB), the 2. 0 version caches all writes regardless of their size and type by increasing the capacity of the pseudo-SLC portion. nCache 1.0 had an SLC portion less than 1GB (SanDisk never revealed the actual size), but the 2.0 version runs 5GB of the NAND in SLC mode for every 120GB of user space.

nCache 2.0 Overview
Capacity 120GB 240GB 480GB 960GB
SLC Cache Size 5GB 10GB 20GB 40GB

The interesting tidbit about SanDisk’s implementation is the fact that each NAND die has a fixed number of blocks that run in SLC mode. The benefit is that when data has to be moved from the SLC to the TLC portion, the transfer can be done internally in the die, which is a feature SanDisk calls On Chip Copy. This is a proprietary design and uses a special die, so you will not see any competitive products using the same architecture. Normally the SLC to TLC transfer would be done like any other wear-leveling operation by using the NAND interface (Toggle or ONFI) and DRAM to move the data around internally from die to die, but the downside is that such a design may interrupt host IO processing since the internal operations occupy the NAND interface and DRAM.

OCZ’s «Performance Mode» is a good example of a competing technology: once the fast buffer is full the write speed drops to half because in addition to the host IOs, the drive now has to move the data from SLC to MLC/TLC, which increases overheard since there is additional load on the controller, NAND interfaces, and in the NAND itself. Performance recovers once the copy/reorganize operations are complete.

SanDisk’s approach introduces minimal overhead because everything is done within the die. Since an SLC block is exactly one third of a TLC block, three SLC blocks are simply folded into one TLC block. Obviously there is still some additional latency if you are trying to access a page in a block that is in the middle of the folding operation, but the impact of that is far smaller than what a die-to-die transfer would cause.

The On Chip Copy has a predefined threshold that will trigger the folding mechanism, although SanDisk said that it is adaptive in the sense that it will also look at the data type and size to determine the best action. Idle time will also trigger On Chip Copy, but there is no set threshold for that either from what I was told.

In our 240GB sample the SLC cache size is 10GB and since sixteen 128Gbit (16GiB) NAND dies are needed for the raw NAND capacity of 256GiB, the cache per die works out to be 625MB. I am guessing that in reality there is 32GiB of TLC NAND running in SLC mode (i.e. 2GiB per die), which would mean 10.67GiB of SLC, but unfortunately SanDisk could not share the exact block sizes of TLC and MLC with us for competitive reasons.

The performance benefits of the SLC mode are obvious. A TLC block requires multiple iterations to be programmed because the distribution of the voltage states is much narrower, so there is less room for errors, which needs a longer and more complex programming process.  

I ran HD Tach to see what the performance is across all LBAs. With sequential data the threshold for On Chip Copy seems to be about 8GB because after that the performance drops from 400MB to ~230MB/s. For average client workloads that is more than enough because users do not usually write more than ~10GB per day and with idle time nCache 2.0 will also move data from SLC to TLC to ensure that the SLC cache has enough space for all incoming writes.

The improved performance is not the only benefit of nCache 2.0. Because everything gets written to the SLC portion first, the data can then be written sequentially to TLC. That minimizes write amplification on the TLC part, which in turn increases endurance because there will be less redundant NAND writes. With sequential writes it is typically possible to achieve write amplification of very close to 1x (i.e. the minimum without compression) and in fact SanDisk claims write amplification of about 0.8x for typical client workloads (for the TLC portion, that is). That is because not all data makes it to the TLC in the first place – some data will be deleted while it is still in the SLC cache and thus will not cause any wear on the TLC. Remember, TLC is generally only good for about 500-1,000 P/E cycles, whereas SLC can easily surpass 30,000 cycles even at 19nm, so utilizing the SLC cache as much as possible is crucial for endurance with TLC at such small lithographies.

Like the previous nCache 1.0, the 2.0 version is also used to cache the NAND mapping table to prevent data corruption and loss. SanDisk does not employ any power loss protection circuitry (i.e. capacitors) in client drives, but instead the SLC cache is used to flush the mapping table from the DRAM more often, which is possible due to the higher endurance and lower latency of SLC. That obviously does not provide the same level of protection as capacitors do because all writes in progress will be lost during a power failure, but it ensures that the NAND mapping table will not become corrupt and turn the drive into a brick. SanDisk actually has an extensive whitepaper on power loss protection and the techniques that are used, so those who are interested in the topic should find it a good read.

Multi Page Recovery (M.P.R)

Using parity as a form of error correction has become more and more popular in the industry lately. SandForce made the first move with RAISE several years ago and nearly every manufacturer has released their own implementation since then. However, SanDisk has been one of the few that have not had any proper parity-based error correction in client SSDs, but the Ultra II changes that.

SanDisk’s implementation is called Multi Page Recovery and as the name suggests, it provides page-level redundancy. The idea is exactly the same as with SandForce’s RAISE, Micron’s RAIN, and any other RAID 5-like scheme: parity is created for data that comes in, which can then be used to recover the data in case the ECC engine is not able to do it.

The parity ratio in the Ultra II is 5:1, which means that there is one parity page for every five pages of actual data. But here is the tricky part: with 256GiB of raw NAND and a 5:1 parity ratio, the usable capacity could not be more than 229GB because one sixth of the NAND is dedicated for parity.

The secret is that the NAND dies are not really 128Gbit – they are in fact much larger than that. SanDisk could not give us the exact size due to competitive reasons, but told us that the 128Gbit number should be treated as MLC for it to make sense. Since TLC stores three bits per cell instead of two, it can store 50% more data in the same area, so 128Gbit of MLC would become 192Gbit of TLC. That is in a perfect world where every die is equal and there are no bad blocks; in reality TLC provides about a 30-40% density increase over MLC because TLC inherently has more bad blocks (e.g. stricter voltage requirements because there is less room for errors due to narrower distribution of the voltage states).

In this example, let’s assume that TLC provides a 35% increase over TLC when the bad blocks are taken away. That turns our 128Gbit MLC die into a 173Gbit TLC die. Now, with nCache 2.0, every die has about 5Gbit of SLC, which eats away ~15Gbit of TLC and we end up with a die that has 158Gbit of usable capacity. Factor in the 5:1 parity ratio and the final user capacity is ~132Gbit per die. Sixteen of those would equal 264GiB of raw NAND, which is pretty close to the 256GiB we started with.

Note that the above is just an example to help you understand how 5:1 parity ratio is possible. Like I said, SanDisk would not disclose the actual numbers and in the real world the raw NAND capacity may vary a bit because the number of bad blocks will vary from die to die. What matters, though, is that the Ultra II has the same 12.7% over-provisioning as the Extreme Pro, and that is after nCache 2.0 and Multi Page Recovery have been taken into account (i.e. 12.7% is dedicated to garbage collection, wear-leveling and the usual NAND management schemes).

Furthermore, all NAND die have what are called spare bytes, which are additional bytes meant for ECC. For instance Micron’s 20nm MLC NAND has an actual page size of 17,600 bytes (16,384 user space + 1,216 spare bytes), so in reality a 128Gbit die is never truly 128Gbit – there is always a bit more for ECC and bad block management. The number of spare bytes has grown as the industry has moved to smaller process nodes because the need for ECC has increases and so has the number of bad blocks. TLC is just one level worse because it is less reliable by its design, hence more spare bytes are needed to make it usable in SSDs.

Testing Endurance

SanDisk does not provide any specific endurance rating for the Ultra II, which is similar to what Samsung is doing with the SSD 840 EVO. The reason is that both are only validated for client usage, meaning that if you were to employ either of them in an enterprise environment, the warranty would be void anyway. I can see the reasoning behind not including a strict endurance rating for an entry-level client drive because consumers are not very good at understanding their endurance needs and having a rating (which would obviously be lower for a TLC drive) would just lead to confusion. However, the fact that SanDisk has not set any rating does not mean that I am not going to test endurance.

To do it, I turned to our standard endurance testing methodology. Basically, I wrote sequential 128KB data (QD1) to the drive and monitored the SMART values 230 and 241, i.e. Media Wear Out Indicator (MWI) and Total GB Written. In the case of the Ultra II, the MWI works opposite of what we are used to: it starts from 0% and increases as the drive wears out. When the MWI reaches 100%, the drive has come to the end of its rated lifespan – it will likely continue to work because client SSD endurance ratings are with one-year data retention, but I would not recommend using it for any crititical data after that point.

SanDisk Ultra II Endurance Test
Change in Media Wear Out Indicator 7.8%
Change in Total GB Written 9,232GiB
Observed Total Endurance 118,359GiB
Observed P/E Cycles ~530

The table above summarizes the results of my test. The duration of the test was 12 hours and I took a few data points during the run to ensure that the results are valid. From the data, I extrapolated the total endurance and used it as the basis to calculate the P/E cycles with the following formula:

I made the assumption that the combined Wear Leveling and Write Amplification factor is 1x because that is plausible with pure sequential writes and it makes the calculation much simpler. For capacity I used the user capacity (240GB i.e. 223.5GiB), so the observed P/E cycles is simply total endurance divided by the capacity (both in GiB).

The number I came up with is 530 P/E cycles. There are a number of factors factors that make it practically impossible to figure out the exact NAND endurance because a part of the NAND operates in SLC mode with far greater endurance and there is a hefty amount of spare bytes for parity, but I think it is safe to say that the TLC NAND portion is rated at around 500 P/E cycles.

SanDisk Ultra II Estimated Endurance
Capacity 120GB 240GB 480GB 960GB
Total Estimated Endurance 54.6TiB 109.1TiB 218.3TiB 436.6TiB
Writes per Day 20GiB
Write Amplification 1.2x
Total Estimated Lifespan 6.4 years 12.8 years 25.5 years 51.0 years

Because the P/E cycle count alone is easy to misunderstand, I put it into context that is easier to understand i.e. lifespan of the drive. All I did was multiply the user capacity by the P/E cycle count to get the total endurance, which I then used to calculate the estimated lifespan. I selected 20GiB of writes per day because even though SanDisk did not provide an endurance rating for the Ultra II, their internal design goal was 20GiB per day, which is a fairly common standard for client drives. I set the write amplification to 1.2x as the TLC blocks are written sequentially thanks to nCache 2.0, and that should result in write amplification that is very close to 1x.

500 P/E cycles certainly does not sound much, but when you put it into context it is more than enough. At 20GiB a day, even the 120GB Ultra II will easily outlive the rest of the components. nCache 2.0 plays a huge role in making the Ultra II as durable as it is because it keeps the write amplification close to the ideal 1x. Without nCache 2.0, 500 P/E cycles would be a major problem, but as it stands I do not see endurance being an issue. Of course, if you write more than 20GiB per day and your workload is IO intensive in general, it is better to look for drives that are meant for heavier usage, such as the Extreme Pro and SSD 850 Pro.

A look at SanDisk’s Updated SSD Dashboard

Along with the Ultra II, SanDisk is bringing an updated version of its SSD Dashboard, labeled as 1.1.1.

The start view has not changed and provides the same overview of the drive as before.

The most important new features are under the «Tools» tab and are provided by third parties. In the past SanDisk has not offered any cloning software with their drives, but the new version brings the option to use Apricorn’s EZ GIG IV software to migrate from an old drive. Clicking the link in the Dashboard will lead to Apricorn’s website where the user can download the software. Note that the Dashboard includes a special version of EZ GIG IV that can only be used to clone a drive once.

In addition to EZ GIG IV, the 1.1.1 version adds Trend Micro’s Titanium Antivirus+ software. While most people are already running antivirus software of some sort, there are (too) many people who do not necessarily have an up-to-date antivirus software that has the definitions for the latest malware, so the idea behind including the antivirus software is to ensure that all users have a free and easy way to check their system for malware before migrating to a new drive.

The new version also adds support for «sanitation». It is basically an enhanced version of secure erase and works the same way as 0-fill erase does: instead of just erasing the data, sanitation writes zeros to all LBAs to guarantee that there is absolutely no way to recover the old data. Crypto erase is now a part of the Dashboard too, although currently that is only supported by the X300s since it is the only drive with hardware encryption support.

Live performance monitoring is also supported, but unfortunately there is no option to run a benchmark within the software (i.e. it just monitors the drive similar to what Windows Performance Monitor does). For OSes without TRIM, the Dashboard includes an option to run a scheduled TRIM to ensure maximum performance. If TRIM is support and enabled (like in this case since I was running Windows 8.1), the TRIM tab is grayed out since the OS will take care of sending the TRIM commands when necessary.

Support has also been improved in the new version as options for live chat and email support have been added. New languages have been added, too, and the Dashboard is now available in 17 different languages. During the install process, the installer will ask for the preferred language, but it is also possible to change that afterwards under the Settings tab.

Test Systems

For AnandTech Storage Benches, performance consistency, random and sequential performance, performance vs transfer size and load power consumption we use the following system:

CPU Intel Core i5-2500K running at 3.3GHz (Turbo & EIST enabled)
Motherboard AsRock Z68 Pro3
Chipset Intel Z68
Chipset Drivers Intel 9. 1.1.1015 + Intel RST 10.2
Memory G.Skill RipjawsX DDR3-1600 4 x 8GB (9-9-9-24)
Video Card Palit GeForce GTX 770 JetStream 2GB GDDR5 (1150MHz core clock; 3505MHz GDDR5 effective)
Video Drivers NVIDIA GeForce 332.21 WHQL
Desktop Resolution 1920 x 1080
OS Windows 7 x64

Thanks to G.Skill for the RipjawsX 32GB DDR3 DRAM kit

For slumber power testing we used a different system:

CPU Intel Core i7-4770K running at 3. 3GHz (Turbo & EIST enabled, C-states disabled)
Motherboard ASUS Z87 Deluxe (BIOS 1707)
Chipset Intel Z87
Chipset Drivers Intel 9.4.0.1026 + Intel RST 12.9
Memory Corsair Vengeance DDR3-1866 2x8GB (9-10-9-27 2T)
Graphics Intel HD Graphics 4600
Graphics Drivers 15.33.8.64.3345
Desktop Resolution 1920 x 1080
OS Windows 7 x64
  • Thanks to Intel for the Core i7-4770K CPU
  • Thanks to ASUS for the Z87 Deluxe motherboard
  • Thanks to Corsair for the Vengeance 16GB DDR3-1866 DRAM kit, RM750 power supply, Hydro H60 CPU cooler and Carbide 330R case

Performance Consistency & TRIM Validation
The Introduction, The Drive & The TestPerformance Consistency & TRIM ValidationAnandTech Storage Bench 2013AnandTech Storage Bench 2011Random & Sequential PerformancePerformance vs. Transfer SizePower ConsumptionFinal Words

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SanDiskUltra II SSD review: A new level of SSD affordability

The SanDisk Ultra II SSD delivers the goods as a budget solid-state drive (SSD).

The new internal storage device is available in 120GB, 240GB, 480GB, and 960GB capacities that cost just $80, $108, $219 and $495, respectively. This is proving to be, for the most part, a new low in SSD pricing.

While the Ultra II isn’t the fastest SSD I’ve seen, nor does it have the longest warranty, the drive has enough performance and features to be an excellent deal for those looking to upgrade an aging computer that’s still running on a regular hard drive.

If you have a computer that already runs on an SSD and you want to upgrade to an even faster drive, check out this list of top SSDs on the market for alternatives.

The SanDisk Ultra II is a new budget standard SSD from SanDisk. Dong Ngo/CNET

A SanDisk drive first: TLC NAND flash memory

The Ultra II is a standard 2. 5-inch 7mm-thick internal drive, looking very similar to the Ultra Plus or even the new Extreme Pro that came out a few months ago.

On the inside, however, it’s very different from its older brothers, being the first drive from SanDisk that uses the company’s second-generation 19nm Triple Level Cell (TLC) flash memory. Prior to this, TLC NAND flash memory was mostly used in Samsung’s drives, such as the Samsung 840 .

In a nutshell, TLC flash memory allows the memory cells to stack up vertically, which in turn packs more storage into the same space. This means the SSD is now cheaper to make but has slower performance and shorter endurance — the total amount of data that can be written to the drive before it become unreliable — than other types of memory, including Multiple Level Cell (MLC) and Single Level Cell (SLC).

SanDisk, however, says that its firmware, combined with the Marvell 88SS9187 controller, will still make the Ultra II perform well and provide high endurance. However, unlike the case of the Extreme Pro, SanDisk doesn’t provide a specific endurance rating for the Ultra II. But the included three-year warranty generally means that you won’t have any problem with it within at least the first three years.

SanDisk Ultra II SSD specs

120GB 240GB 480GB 960GB
Interface SATA 6Gbps SATA 6Gbps SATA 6Gbps SATA 6Gbps
Controller Marvell 88SS9187 Marvell 88SS9187 Marvell 88SS9187 Marvell 88SS9187
NAND flash memory SanDisk 2nd Gen 19nm TLC SanDisk 2nd Gen 19nm TLC SanDisk 2nd Gen 19nm TLC SanDisk 2nd Gen 19nm TLC
Sequential read 550 MB/s 550 MB/s 550 MB/s 550 MB/s
Sequential write 500 MB/s 500 MB/s 500 MB/s 500 MB/s
Random read 81K IOPS 91K IOPS 98K IOPS 99K IOPS
Random write 80K IOPS 83K IOPS 83K IOPS 83K IOPS
Warranty 3 years 3 years 3 years 3 years

nCache 2.

0 technology

The Ultra II is equipped with SanDisk’s nCache 2.0 tech, a new caching architecture that converts a portion of the drive’s TLC flash memory to SLC mode, thus offering better performance and reliability. This means the drive can deliver much faster peak performance than it would normally without nCache. SanDisk says nCache 2.0 will also help deliver consistent performance with low energy consumption.

The drive also includes SanDisk Dashboard software that allows users to monitor and manage the drive’s features, as well as contacting the company’s customer support via Live Chat. On top of that, the software also provides links to download Apricorn’s EZ GIG IV for drive cloning, and Trend Micro Titanium Antivirus+ to protect the system from malware, both for free.

The SanDisk Dashboard software is a handy utility. Screenshot by Dong Ngo/CNET

New low in SSD pricing

For a long time, SSDs were priced at around $1 per gigabyte, but in recent months, the price has dropped to around half of that. Now with the Ultra II, for the first time you can get a 960GB SSD in the US for just $380, or 40 cents per gigabyte. Other than the 120GB capacity that costs $80 ($0.67 per gigabyte), the rest of the Ultra II’s capacities are currently the most affordable on the market.

In most cases, it’s in fact cheaper than the ARC 100 series from OCZ , which used to be the cheapest on the market. With the Ultra II, SSD pricing has gotten to a new low, which is always a great news for consumers.

SSD US street price

WD Black 2 Dual Drive $0.18SanDisk Ultra II (960GB) $0.40SanDisk Ultra II (480GB) $0.42SanDisk Ultra II (240GB) $0.45OCZ ARC 100 (240GB) $0.50Samsung SSD 840 Evo (256GB) $0.51Plextor M6S (256GB) $0.53OCZ Vector 150 (480GB) $0.58Samsung SSD 840 Pro (256GB) $0.64SanDisk Ultra II (120GB) $0.67Intel SSD 730 (240GB) $0.70SanDisk Extreme II (240GB) $0.73SanDisk Extreme Pro (240GB) $0.75Samsung SSD 850 Pro (256GB) $0.78

Note: Measured in cost per gigabyte, based on current prices at online retailers. A lower number indicates better value.

Performance

Considering its low cost, the Ultra II’s performance was quite impressive. I tested the drive both as a secondary drive in a computer as well as the main drive that hosted the operating system.

As a secondary drive, it registered a sustained real-world data transferring speed of 310MBps for writing and 310MBps for reading. When used as a main drive and performing both writing and reading at the same time, it, however, scored just 127MBps. Overall, it was below average when compared to recently reviewed drives, but most of these are high-end drives, however.

CNET Labs’ SSD data transfer scores

Samsung 850 Pro 246.25 454.32 448.11SanDisk Extreme Pro 250.98 450.59 457.46OCZ ARC 100 series 163.53 289.39 385.71Plextor M5 Pro Xtreme 236.18 269.78 270.8Intel SSD 730 Series 189.52 265.53 266.84OCZ Vector 150 231.42 265.32 200.46Seagate 600 SSD 192.26 259.01 275.21SanDisk Extreme II 224.27 255. 86 203.42Transcend SSD720 145.26 230.58 269.55SanDisk Ultra II 126.49 210.21 319.23Plextor M6S 155.34 144.78 227.89WD Black 2 Dual Drive 174.65 114.66 228.2

  • As OS drive (read and write)
  • As secondary drive (write only)
  • As secondary drive (read only)

Note: Measured in megabytes per second.

In tests using the PCMark benchmark suite, the drive also did as expected. It has slightly higher storage bandwidth than that of the OCZ ARC 100.

PCMark 8 SSD storage score

Samsung 850 Pro (RAPID 5005 368.13Samsung 850 Pro 4979 267.32SanDisk Extreme Pro 4957 244.17Plextor M5 Pro Xtreme 4948 236.18SanDisk Ultra II 4922 208.55OCZ ARC 100 series 4948 203.72

  • Storage score
  • Storage bandwidth (MB/s)

Note: Higher number means better performance.

And finally, in application testing, the Ultra II offered much improvement when compared with a conventional hard drive. Compared with other high-end SSDs, it was slightly slower, though not by much.

PCMark 8 application performance

Samsung 850 Pro (RAPID) 58 133.9 355.7 28.2 9.1 9.1Samsung 850 Pro 58.1 133.8 369.8 28.3 9.1 9.2SanDisk Extreme Pro 58.4 133.9 361.1 28.3 9.2 9.2SanDisk Ultra II 58.8 134.6 363.1 28.4 9.3 9.3OCZ ARC 100 series 58.9 134.7 362.3 28.4 9.4 9.3Standard laptop HDD 138.9 366 565.19 51.7 26.6 27.4

  • World of Warcraft
  • Battlefield 3
  • Adobe Photoshop
  • Microsoft Word
  • Microsoft Excel
  • Microsoft PowerPoint

Note: Measured in seconds. Shorter bars means better performance.

Note that you need to use the Ultra II in a computer that supports SATA 3 (6Gbps) to get the best performance out of it. However, considering its low cost, the drive will still make a great upgrade for an older computer that supports SATA 2 (3Gbps).

Conclusion

Pricing has always been one the most important factors in buying an SSD, and SanDisk delivers in this regard with the Ultra II. It’s the first on the market that a cost as low as just 40 cents per gigabyte.

The new drive is also SanDisk’s first step in the TLC SSD market, which has been dominated by Samsung. This opens up the competition and means that, going forward, the price of SSDs will be likely to go down even further.

While the Ultra II isn’t the fastest on the market, it has enough power to make a significant improvement to any computer that currently runs on a regular hard drive. For this reason, instead of spending a few hundred dollars for a new budget computer, upgrading your aging one with a 240GB Ultra II SSD for $108 will be a much better investment that, for the most part, will return the type of performance you need.

SanDisk Ultra II 240GB Review

Verdict

Pros

  • Consistently decent performance
  • First non-Samsung consumer TLC SSD
  • 9. 5mm blanker included

Cons

  • Samsung 850 Evo is only £10 more
  • No endurance rating provided

Key Specifications

  • Review Price: £100.00
  • 240GB capacity (223GB formatted)
  • 7mm form factor
  • SATA 3 interface
  • 3yr RTB warranty

What is the SanDisk Ultra II 240GB?

The latest drive from storage specialists SanDisk is a mid-range product that really shows how far SSDs have come – it’s not long ago that a 240GB drive costing £100 would have raised plenty of eyebrows.

The Ultra II’s £100 price means it costs just under 42p per gigabyte. That puts it in an interesting position: cheaper than the Samsung 850 Evo, which arrives at 44p per gigabyte, but not as affordable as the 30p-per-gigabyte Crucial MX100.

SEE ALSO: Best SSDs Round-up

SanDisk Ultra II 240GB – Design

The mid-range price hasn’t prevented SanDisk from trying something new with the Ultra II. This is the first SanDisk SSD to deploy TLC NAND, and the first time it’s been used inside a consumer drive that doesn’t bear the Samsung brand. That’s a big move, and it’s taken some time – Samsung first debuted TLC drives way back in 2012.

The choice of TLC memory comes with pros and cons. The cells used to form this drive’s memory can hold three bits of data each, which increases density – so the same amount of silicon has more space for storage. That helps bring the cost down, but it also hampers performance, as electricity has more distance to travel inside each of those cells.

Elsewhere the Ultra II is more conventional. The memory used is built on a 19nm manufacturing process and using horizontal layers, rather than the 40nm vertical layers chosen by Samsung for its 3D V-NAND system.

SanDisk uses two Marvell controllers inside Ultra II drives. The smaller 120GB and 240GB models use 88SS9190 hardware, while the 480GB and 960GB versions deploy 88SS9189 hardware. The former is a four-channel controller, while the latter is an eight-channel chip – a choice that SanDisk has likely made due to the higher demands of its larger drives. The latter is also the same controller used by Crucial in its MX100.

SanDisk’s drive comes with a feature called nCache, which uses 10GB of the 240GB drive’s space in an SLC-style caching mode. It’s a neat feature that will improve response times when dealing with frequently-accessed files. It’s reminiscent of Samsung’s Rapid Mode, but SanDisk hasn’t found room in this drive for any encryption.

We usually talk about endurance ratings when discussing an SSD’s specification, but SanDisk doesn’t publish these for the Ultra II. That shouldn’t be a problem for most home or gaming PCs, which don’t put huge demands on SSDs when it comes to writing data, but those after a drive for intensive work should look elsewhere.

SanDisk Ultra II 240GB – Performance

TLC memory isn’t the
fastest, and the Ultra II’s lack of raw pace was exposed in our AS SSD
benchmarks. In the sequential read test the Ultra II managed 505MBps – a
mid-range result that’s not as good as the MX100’s 519MBps pace. The
SanDisk beat the MX100 with a file write speed of 473MBps, but that
result wasn’t enough to lift it beyond mid-table – and it wasn’t enough
to beat the Samsung 850 Evo, either.

The situation wasn’t much
better when handling smaller files. The SanDisk’s 4K read and write
speeds of 30MBps and 72MBps both fell behind the MX100, and in the 4K-64
benchmark it trade blows with its cheaper rival – faster when reading,
but slower when writing. None of these scores could match Samsung’s Evo,
which remained convincingly ahead throughout these tests.

The
Ultra II hit its stride in our Atto benchmarks, which evaluate
performance across a wide range of file sizes. In the 8K test the
SanDisk returned read and write speeds of 407MBps and 391MBps, with both
scores miles ahead of anything the Crucial could manage. That lead was
maintained across the rest of our tests, too: when reading files the
SanDisk’s peak of 558MBps snuck ahead of the MX100’s top score of
552MBps, but when writing the Ultra’s top pace of 507MBps was much
better than the Crucial’s 346MBps result.

The SanDisk’s read peak
was better than the Samsung Evo, too, although the Samsung fought back
with a top write result of 530MBps.

The good form didn’t continue
in the IOMeter tests. In the all-in-one benchmark the Ultra II’s result
of 1843 I/Os proved sluggish – around 600 points behind the Crucial,
and several times slower than top SSDs from Samsung. The SanDisk’s raw
speed of 70MBps was similarly poor – slower than both drives – and its
average response time lagged behind, too.

Samsung’s Evo, meanwhile, beat both drives: its top all-in-one score was 5,270 I/Os, and it topped out at 202MB/s.

Other things to consider

The
Ultra II includes a three-year warranty, which is about what we now
expect from affordable SSDs – that deal matches what’s on offer from the
MX100. That said, it’s two years short of the Samsung 850 Evo’s
coverage.

We no longer expect plenty of accessories inside SSD
boxes, but that hasn’t stopped SanDisk including a 9.5mm spacer with the
Ultra II. It’s a handy bit of kit that enables this 7mm drive to fit
into spaces designed for 9.5mm hardware, which means it could be easier
to fit the Ultra II inside older PCs and laptops without the SSD
rattling around.

Three other capacities of Ultra II are
available. The 120GB is the cheapest at just £55, but that’s
46p per gigabyte – a little higher than the
240GB version we’ve reviewed. The 480GB version costs £155 or
32p per gigabyte, and the mammoth 960GB model is £342, which works out
at 36p per gigabyte.

Should I Buy the SanDisk Ultra II 240GB?

The
240GB option costs a reasonable £100, which makes it one of the cheaper
SSDs we’ve seen recently. The modest price and TLC architecture means
mid-table performance, but that’s not necessarily a bad thing – in AS
SSD the Ultra II traded blows with the Crucial MX100, and the SanDisk
secured a convincing victory over its rival in the comprehensive Atto
suite.

The Ultra II faltered in IOMeter, where the MX100 proved a
tad faster, but neither of these affordable SSDs could match top-end
drives for pace – in the greater scheme of things, the Ultra II didn’t
lose much ground.

The reasonable AS SSD pace and solid Atto
performance mean we’d rather buy the SanDisk than the Crucial drive –
it’s more expensive, but it’s faster and a little more consistent.
There’s a sting in the tale, though, and it’s Samsung’s 850 Evo – it’s
only ten pounds more expensive, but it’s faster and has a better
warranty. Unless budget is important, we’d opt for the Evo.

SEE ALSO: Best Laptops Round-up

Verdict

The
Ultra II is faster than the Crucial MX100 in several key benchmarks,
and we’d be happy paying the extra cash for it. There’s a sting in the tale, though, from
Samsung’s 850 Evo, which is faster and only £10 more expensive.
The Ultra II is a good effort, but it’s not quite good enough.

SanDisk Ultra Plus SSD review: Fast and inexpensive

Review

A solid state drive meant specifically to replace aging hard drives.

By Lucas Mearian

Senior Reporter,

Computerworld |

When SanDisk announced the arrival of its Ultra Plus solid-state drive (SSD) at CES two weeks ago, the company made no bones about whom it was targeting: the consumer retrofit market. In other words, this SSD was made specifically to replace that old hard drive in your laptop or desktop.

SanDisk Ultra Plus SSD

Right off the bat I liked two things about this drive: It’s extremely light (it only weighs 1.37 oz.) and it’s cheap — as in very inexpensive. The Ultra Plus comes in 64GB, 128GB and 256GB capacities. On SanDisk’s site, they sell for $75, $110 and $210, respectively. The 256GB Ultra Plus — which is the one I tested for this review — was selling for $170 on Thursday on Amazon, although the price as of today is $216.

As I’ve said in past reviews, there is no single upgrade that will give you a bigger bang for the buck than an SSD, and it’s all the better when it’s an inexpensive one.

The Ultra Plus is a 2.5-in drive that uses multi-level cell (MLC) NAND flash and a SATA 3.0, 6Gbps drive interface. If you don’t have the very latest laptop or desktop model, you are likely still using a SATA 2.0, 3Gbps drive interface, so the SSD won’t perform quite as well for some applications. (The Apple MacBook Pro I tested the drive on has the latest SATA drive dock; more information about my test machine is in the next section. )

When SanDisk announced the Ultra Plus, the company also announced an upgrade to its NAND flash density: it went from 24-nanometer (nm) lithography to 19nm with the drive, which may account for the low price. The smaller the technology used for the semiconductor, the fewer chips are needed to build a drive.

The Ultra Plus sips power, using just 0.12 watts when active.

Performance testing

SanDisk’s specification sheet (PDF) states that the Ultra Plus has sequential read speeds of up to 530MB/s and sequential write speeds of up to 445MB/s. Top random read speed clocks in at up to 82,000 I/Os per second (IOPS) and random write speed maxes out at 39,000 IOPS. As always, those speeds vary greatly depending on the system and apps that are being used.

For the benchmark tests, I used an Apple MacBook Pro running OS X Mountain Lion, with 4GB of RAM and a 2.5GHz Intel Core i5 processor. To measure data read/write performance, I used Blackmagic Disk Speed Test benchmark software.

The Ultra Plus SSD displayed blazing fast read/write performance — among the fastest speeds I’ve seen on a consumer SSD. For reads, the SSD clocked in with 433MB/s; for writes, the drive reached 339MB/s., not as fast as SanDisk’s spec sheet promised but still very impressive.

With the Ultra Plus installed, my MacBook Pro booted in just 14 seconds, which isn’t bad. (Interestingly, the time it took to shut down was a bit surprising. While, in my experience, SSDs typically shut down in under 10 seconds, my laptop took a whopping 24 seconds to shut down with the Ultra Plus installed. )

SSD and HDD performance test results
SanDisk Ultra Plus SSD Intel 520 Series SSD Western Digital WD Black HDD
Capacity 256GB 240GB 500GB
Retail price (approx.) $210 $245 $64
Boot time 14 sec. 9 sec. 21 sec.
Max. read speed (4K blocks) 433MB/sec. 456MB/sec. 122MB/sec.
Max. write speed 339MB/sec. 241MB/sec. 119MB/sec.

Read/write speeds tested using Blackmagic Disk Speed Test. Higher numbers are better.

How does that performance compare? Last year, I tested Intel’s fastest consumer drive, the 520 Series SSD. The Intel 520 Series clocked in with 456MB/s read and 241MB/s write speeds. That SSD also booted in nine seconds.

However, while the Intel 520 Series is faster than the Ultra Plus, you’ll also pay a bit more. For example, prices for the 240GB model start at $245, as compared to the 256GB Ultra Plus that can be found at $170.

I also compared the drive with what would typically come in a laptop: a hard drive. I tested the same MacBook Pro with a Western Digital WD Black 500GB drive, and saw maximum speeds of 122MB/s for reads and 119MB/s for writes. Using the hard drive, the system booted in 21 seconds, nearly double that of the Ultra Plus.

Of course, a hard drive is also a lot easier on your wallet. The WD Black 500GB drive retails for just $64.

Bottom line

Overall, I was impressed with the SanDisk Ultra Plus SSD. The boot times were excellent, as were the data transfer speeds. The shutdown time was a bit disappointing, but nothing that would dissuade me from purchasing this affordable drive.

Lucas Mearian covers storage, disaster recovery and business continuity, financial services infrastructure and health care IT for Computerworld. Follow Lucas on Twitter at  @lucasmearian or subscribe to Lucas’s RSS feed . His e-mail address is [email protected]

See more by Lucas Mearian on Computerworld.com.

Related:

  • Solid-State Drives
  • Data Management
  • Intel

Senior Reporter Lucas Mearian covers Windows, Future of Work issues, mobile, Apple in the enterprise, and healthcare IT.

Copyright © 2013 IDG Communications, Inc.

7 inconvenient truths about the hybrid work trend

SanDisk Ultra II 240GB SSD Review — SanDisk’s First TLC NAND SSD

The Ultra II Gets TLC With A Dash Of SLC – SanDisk’s First TLC NAND SSD

When Samsung released their 840 Series drive back near the end of 2012, it was the first consumer drive to feature TLC (Triple Level Cell) NAND which took everyone by surprise as up until then, MLC drives ruled the consumer roost. The drive proved to be quite popular with decent performance and stellar power usage along with a very modest price tag. SanDisk has decided to drop some TLC NAND into their second iteration of the Ultra series drives which should provide some solid performance numbers along with budget level pricing. Without peeking at the specifications, we surmised that performance would be above average with low power consumption and we weren’t wrong.

SanDisk has really been coming on strong in the SSD market and should be considered one of the premiere drive makers given their expertise and access to raw materials and manufacturing. As such, it didn’t come as a total surprise to see them out a TLC based drive but there are many in the industry don’t believe TLC is a viable long term component for client SSDs. Enter the SanDisk Ultra II Solid-State Drive. Available in capacities of 120GB, 240GB, 480GB and 960GB, it covers all the bases while offering a splendid read/write rating of up to 550MB/s and 500MB/s respectively. IOPS specifications are solid too with reads and writes all above 80K and then some depending on the model. So far, it’s only available as 2.5″ drive although they could easily make an M.2 or mSATA drive given the size of the PCB in the review sample we received (check out page 2).

If you don’t recall, TLC is technically a form of MLC (Multi-Level Cell) and contains three bits per cell rather than the two in MLC and the one in SLC. The diagram below shows, at a high level, how this works. With more data per cell, TLC NAND can cram in more dies per package and is generally a little cheaper to manufacture than MLC and a lot cheaper than SLC. The downside is, it’s generally slower and because of increased write-amplification its overall endurance is typically less than the others. Having some SLC on board to cache the data before flushing to the TLC greatly reduces the write-amplification and therefore drive endurance is improved.

SanDisk Ultra II Specifications and Features

Specification: Parameter: 120GB 240GB 480GB 960GB
Part Number: SDSSDHII-120G-G25 SDSSDHII-240G-G25 SDSSDHII-480G-G25 SDSSDHII-960G-G25
MSRP/Retail: $79. 99 / $79.99 $114.99 / $109.99 $219.99 / $199.99 $429.99 / $379.99
Flash: SanDisk 1Ynm, X3 ABL, Toggle
Interface: SATA 6GB/s backward compatible
CrystalDiskMark:
Seq Read (up to): 550MB/s 550MB/s 550MB/s 550MB/s
Seq Write (up to): 500MB/s 500MB/s 500MB/s 500MB/s
Rnd Read (up to): 81K IOPS 91K IOPS 98K IOPS 99K IOPS
Rnd Write (up to): 80K IOPS 83K IOPS 83K IOPS 83K IOPS
Power (typical):
Active Power: 85mW 85mW 85mW 85mW
Max Read Operating: 2. 5 W 2.7 W 2.7 W 2.9 W
Max Write Operating: 3.3 W 4.5 W 4.5 W 4.6 W
Slumber: 75mW 75mW 85mW 85mW
MTBF: Telcordia, Stress Part 1.75 Million Hours
Weight: Individual Product: 58 g 58 g 58 g 61 g
Size: 2.5″ SFF-8223 & -8201: 70mm x 69.85mm x 100.5mm
Environmental: Operating Temp: 0C to 70C
Non-Operating Temp: -55C to 85C
Warranty: 3 Year limited warranty
  • SATA 8Gb/s Compliant
  • ATA-ACS v6
  • NCQ support upo to queue depth = 32
  • Support for TRIM
  • S. M.A.R.T. feature supported
  • Advanced Flash Management:
    • nCache 2.0 – Non Volatile Write Cache
    • Multi-Page Recovery
    • XOR Recovery
    • Dynamic and Static Wear-leveling
    • Bad Block Management
    • Backgrounf Garbage Collection
  • Advanced features:
    • Tiered caching – Volatile and non-volatile cache
    • Supports multi stream – improves user experience in multitasking systems
    • Minimal write amplification – increase endurance and performance
  • Support For Thermal Throttling:
    • Performance will be throttled in the event junction temperature of critical components is measured to be exceeding the maximum allowable for the product

Along with the TLC NAND is a host of other technical features on the Ultra II that makes everything work. They are all there to bolster performance and mitigate undue wear on the drive as TLC has a lower endurance rating than MLC.

SanDisk’s nCache 2.0 technology leverages tiered caching to handles this process and all the while improving write performance as an added perk. The nCache process assures all of the data is written to the SLC blocks initially prior to flushing to the TLC. Note that the diagram indicates that the number of channels is split between four and eight channels because the 120GB and 240GB drives use a four channel controller and the larger capacities use an eight channel controller. This is simply because on the larger drivers, the are more than four dies available in the array.

Since, as our diagram above illustrated, there are three bits of data in TLC cells versus the one in SLC, the data that is cached in SLC is “folded” in triplet to the TLC cells. Since this is handled on die, any extra overhead on the controller is mitigated and latency is not unduly impacted. This “On Chip Copy” as they term it, is unique to SanDisk and is the most efficient method of handling this process that we’ve seen.

A big concern with SSDs is accuracy and the need for error correction. In addition to the normal controller ECC, SanDisk is leveraging what they call Multi Page Recovery (M.P.R.) to handle error correction by means of parity and redundancy of pages. If an error is detected that ECC cannot recover, the page is recovered thanks to the redundancy and all is right with the world again. The illustration actually does a nice job of showing what occurs.

Finally, we’ve discussed the SanDisk Dashboard application before and it’s a super nice tool for checking out drive metrics, secure erasing, updating firmware. They’ve made a few improvements in this version including support for 17 languages, a sanitize function, crypto erase and assistance from “Live Chat” or ask a tech support question via buttons in the GUI. Bundled with the SSD Dashboard is a suite of software tools although all are either limited or trial versions. First is cloning software from Apricorn call EZ GIG IV, then Trend Micro Titanium Antivirus+ and rounded out with Absolute LoJack security software.

Questions or comments?
View this thread in our forums!

Sandisk Ultra 3D SSD review: Big capacity, fast performance

Reviews

Faster than all the TLC NAND SSDs we’ve tested to day, and available in up to 2TB capacity

By Jon Jacobi

Freelance contributor, PCWorld

Sandisk

At a Glance

Expert’s Rating

Pros

  • Very good overall and sustained performance
  • Affordable in all capacities

Cons

  • A bit slow reading smaller files and folders
  • 2TB version has a lower TBW rating

Our Verdict

The Ultra 3D and its nearly identical WD Blue 3D sibling are a step up from TLC drives in performance, but deliver the same 1TB and 2TB of capacity at roughly the same price. Not as fast as SSDs such as Kingston’s HyperX Savage and Crucial’s BX300, but not limited in capacity. Short list.

There are still lots of PCs out there that would take on new life with a simple hard-drive-to-SSD upgrade, and Sandisk’s Ultra 3D is one of the best, if not the best SSD for the job. Using the same 3D (stacked, or layered) TLC NAND found in the WD Blue 3D SSD we also tested (WD owns Sandisk) it offers the capacity of TLC without the write performance penalties we’ve experienced previously.

The Sandisk Ultra 3D comes in the standard SATA 6Gbps, 2.5-inch, 7mm-thick form factor that’s the norm for the category these days. Being only 7mm thick means it’s suitable for upgrading a number of mid-sized and desktop replacement laptops. (The closely related WD Blue 3D—Western Digital owns Sandisk—also ships in the M.2 form factor, if that’s what you need.)

Though most users will only see the Ultra 3D when installing it in a computer, we should note that the Ultra 3D is a notch above the average drive in appearance—black, with a classy red logo. If you’re filling out the storage on a gaming rig with clear panels, that could be a consideration.

Mentioned in this article

Ultra 3D SSD 250GB

The Ultra 3D is available in 250GB, 500GB, 1TB (the size we tested), and 2TB capacities, which we saw online for about $100, $165, $285, and $550 respectively. That’s around 25 cents per GB in the highest capacity. The 250GB model is rated for 100TBW (TeraBytes Written) over the lifetime of the drive, the 500GB model for 200TBW, the 1TB version for 400TBW, and the 2TB version for 500TBW.

We’re not sure why the TBW rating for the largest capacity would drop from 40 percent per GB to 25 percent. Perhaps it’s not over-provisioned as heartily—in other words, there’s not as much extra NAND on board to replace worn-out cells. All capacities are covered by a 3-year warranty.

Performance

The Ultra 3D’s good performance is notable for not suffering the write performance penalty you see when similarly priced TLC NAND-based drives run out of cache. WD/Sandisk claims this is due to a more multi-tiered caching technique combining TLC and TLC treated as SLC. That’s what everyone else does, but apparently WD is either better at it, or uses more cache. We threw an extra 320GB data set at it to make sure it could sustain the pace. It did.

We test using AS SSD and CrystalDiskMark, then back that up with real-world copying of a single large 20GB file, as well as a 20GB mix of smaller files and folders.

As you can see below, there’s not a whole lot of difference between the Ultra 3D’s performance and that of MLC drives. Note the lack of a dropout in the AS SSD 10GB write test, where the Samsung EVO series and other TLC drives suffer.

IDG

The Sandisk Ultra 3D is faster overall than any other TLC drive we’ve tested.

The Ultra 3D didn’t write our 20GB mix of files and folders as quickly as we’d hoped, but it’s still a good performer overall. And certainly faster writing than the Samsung EVO series.

IDG

For some reason, as you can see in the chart above, the Ultra 3D didn’t fare all that well reading our 20GB mix of files and folders, but overall, it’s still a better performer than the Samsung 750 EVO. And it’s certainly ballpark in most respects with the average MLC NAND SSD.

Conclusion

The Sandisk Ultra 3D doesn’t displace the Crucial BX300 as our current top choice among bargain or mid-range SSDs, unless you need more than that drive’s 480GB maximum capacity. Then it’s the Ultra 3D for sure, even over the Samsung 750 EVO.  Fast, affordable, good-looking, a nice TBW rating… What’s not to like?

Note: This article was edited to reflect new testing with a 320GB data set rather than the 80GB data set used originally.

Author: Jon L. Jacobi, Freelance contributor

Jon Jacobi is a musician, former x86/6800 programmer, and long-time computer enthusiast. He writes reviews on TVs, SSDs, dash cams, remote access software, Bluetooth speakers, and sundry other consumer-tech hardware and software.

new under the guise of the old (page 2)

Visual inspection

SanDisk Plus and SanDisk Ultra II are also different: in the first case it is an all-plastic case, in the second — plastic and metal.

Both drives are labeled on the bottom with technical information: name, capacity, and serial number. But there is no data on the factory version of the firmware.

If we talk about SanDisk Plus, then there is one more important point, but more on that later.

Shortened printed circuit boards with double-sided mounting of the element base are hidden inside both heroes of the review.

recommendations

At the same time, the SanDisk Ultra II printed circuit board contacts the case through a thermal pad, while SanDisk Plus, as a more budgetary SSD, is deprived of such a pleasant bonus. However, given that the case is completely made of plastic, there would still be no normal heat dissipation (and, looking ahead, let’s say that in vain).

And here a surprise appeared: not only 19 nm memory, but also Marvell 88SS9189 and 88SS9190 controllers are a thing of the past. It turns out that now the SanDisk Ultra II is completely identical in hardware to the SanDisk X400 and WD Blue SSD — they also use SanDisk 05478 064G memory chips and the Marvell 88SS1074 NAND controller.

Plextor M7V and Kingston UV400 are close relatives — they use the same controller and TLC NAND memory, manufactured according to the 15 nm process technology (Toshiba and SanDisk have been working together on NAND in recent years), but with different settings at the microcode level .

The current SanDisk Plus is based on the Silicon Motion SM2256S controller, which, interestingly, does not have external buffer memory in this case. SanDisk 05498 064G memory chips (by the way, 15 nm TLC NAND, as in SanDisk Ultra II) from SanDisk Plus can also be found under the WD brand — in WD Green SSD, but just these drives are not completely identical: as part of WD Green Silicon Motion SM2258XT NAND controller is used. Of the direct analogues, I can now only recall the SanDisk Z410. Thus, the early SanDisk Plus and the modern one are also fundamentally different SSDs.

Curiously, the Silicon Motion website only mentions SM2256, without any additional prefixes in the designation, despite the fact that there are at least three versions of it: SM2256K (ADATA Premier SP550, Geil Zenith R3, AMD Radeon R3, Colorful SS500P, Mushkin Triactor), SM2256G (Crucial BX200, Transcend SSD220S) and SM2256S (SanDisk Plus G26/J26, SanDisk Z410). The first two are with external buffer memory, the third one, as we can see, has no buffer memory chips. At the same time, the dimensions of the chips of these controllers are the same, which may indicate the lack of integration of DRAM crystals, as, for example, Toshiba does with Marvell controllers, and the dimensions of the chips are «real» — judging by the layout of printed circuit boards, pin compatibility is not observed.

Indirectly in favor of the lack of this kind of integration is the fact that the 480 GB SanDisk Z410 / Plus I saw use exactly the same printed circuit board, the difference is only in larger flash memory chips — 512 MB DRAM is quite difficult to pack into a controller chip. Most likely, DRAM is still packed into the SM2256S chip, but a very small fixed amount, for example, 32 MB, like in the Phison S11.

In total, the volume of both SanDisk models is 256 GB, available to the user — 240. At the same time, the user volume is traditionally indicated in decimal system (1 GB is used equal to 1,000,000,000, not 1,073,741,824 bytes), and therefore in reality the user only 223. 57 GB available. The controller firmware uses the remaining volume for service purposes: for wear leveling, as a backup pool for replacing failed memory cells, storing checksums, and so on.

We have already noted several times the fact of a radical change in the hardware platform in SanDisk Plus. But how to distinguish them? In fact, this is possible — according to the article code. For SanDisk Plus, this designation is SDSSDA-***G-***, where the first group of asterisks corresponds to the volume (120, 240, 480 GB), and the second is a letter and two numbers. The letter indicates the geographic location (G — global market, J — Japan — Japanese market), and two numbers — our desired distinguishing feature: 25 — SM2246XT and MLC NAND, 26 — SM2258 and TLC NAND.

The trouble is that not all stores, when forming their price lists, pay attention to this feature, and some do not distinguish SanDisk Plus modifications at all, indicating old specifications in the catalog, and therefore, often with a purposeful purchase of the G25 in a store, they can give G26.

And then there’s SanDisk itself complicated identification:

The label on the SanDisk Plus case only lists the first two label groups, SDSSDA-***G. The key third can only be found on the packaging. If this is not a problem with a new drive, then with the acquisition in the secondary market there will be additional difficulties.

However, which modification to give preference to is not at all an unambiguous question, as one might think. SanDisk Plus (and its corporate counterpart SanDisk Z400s), like a number of other SSDs based on the Silicon Motion SM2246XT controller, is a vivid example of how engineering errors are discovered not during classic tests, but as a result of practical operation: it turned out that with a strong filling drive (approximately 85-90% of user space), the internal activity of the device increases dramatically.

The end result of this is a literally soaring Write Amplification: for some of the samples I saw, it reached 1300-1500 (in other words, for every 1 GB of data from the system, there were ~ 1. 3-1.5 TB of writing to flash memory). As a result, the flash memory array wore out in a matter of months, and the drive failed.