The SSD market is currently going through the biggest change in its history. Ever since consumer SSDs started appearing around 2006, SATA has been the dominant interface but now that is about to change. With PCIe and NVMe making their way to the consumer space, SATA will sooner than later become obsolete, at least for high performance SSDs.

But right now, it is way too early to bury SATA. The transition to PCIe has taken its first baby steps but is far from taking over SATA. I believe 2015 will be the year of PCIe SSDs, because by then we will have several PCIe SSD platforms ready from SandForce, JMicron, and others; then the OEMs can start shipping drives in volume. However, we are still six months away from 2015 and even then, SATA is not going anywhere. The market and drives will continue to evolve and the latest proof comes from SanDisk with a humble name: the Extreme Pro.

The Extreme Pro takes the proven recipe of the Extreme II. The controller is unchanged but the firmware has been optimized even further for consistency and the NAND has been changed to SanDisk's own second generation 64Gbit 19nm MLC (same as Toshiba's A19nm). SanDisk's target markets for the Extreme Pro are gamers and professionals, which are user groups that traditionally crave performance and consistency.

The Extreme II had excellent IO consistency to begin with and was one of the most consistent client drives we have tested, so the bar is set high for the Extreme Pro. SanDisk is so confident about the reliability of the Extreme Pro that it is giving it a 10-year warranty, which is twice of what any consumer-grade SSD has offered so far.

SanDisk Extreme Pro Specifications
Capacity 240GB 480GB 960GB
Controller Marvell 88SS9187
NAND SanDisk 2nd Generation 64Gbit 19nm MLC
DRAM 512MB 1GB 1GB
Sequential Read 550MB/s 550MB/s 550MB/s
Sequential Write 520MB/s 515MB/s 515MB/s
4KB Random Read 100K IOPS 100K IOPS 100K IOPS
4KB Random Write 90K IOPS 90K IOPS 90K IOPS
Idle Power (DevSLP/Slumber) 5.5mW / 82.5mW 19mW / 100mW 19mW / 100mW
Load Power (Read/Write) 2.7W / 2.6W 2.7W / 3.5W 2.9W / 3.6W
Endurance 80TB (~22GB per day for 10 years)
Encryption No
Warranty 10 years

SanDisk dumps the 120GB model from the Extreme Pro lineup but adds a 960GB one. This move makes sense because 120GB cannot provide the same level of performance due to the lack of NAND but also falling NAND prices have made 1TB-class SSDs affordable for consumers. I am a bit surprised that SanDisk has decided to use 64Gbit parts in all models because usually 1TB-class SSDs have required the use of bigger 128Gbit dies. I guess it helps that the page size is 16KB for the 64Gbit part too because the main problem with high capacity SSDs is that when you double the capacity, the amount of pages you need to track doubles as well. With both 64Gbit and 128Gbit parts having the same page size, the issue is pretty much neutralized as long as the controller and firmware can talk to that many NAND die (this is where having your own firmware team helps). 

Photography by Juha Kokkonen

The PCB in the Extreme Pro is single-sided in all models. There are eight NAND packages, which means that the 960GB drive must be using 16-die packages to achieve such high capacity. 16-die packages are actually nothing new because SanDisk and others have used them, and even 32-die packages, in memory cards for quite some time.

SanDisk's 16-die package used in 128GB iSSD

However, the yields are lower because it takes more precision to stack 16 dies and connect all the wires, which is why most manufacturers only use 8-die packages in SSDs. For memory cards one NAND package is enough because there is no space for more, but SSDs need several packages. Yields do get better over time though, and SanDisk's 16-die packaging is apparently economical enough to be used in SSDs now. There are some latency obstacles as well because taller stacks require longer wires, but it looks like the drawback is not enough to prevent their use in high performance SSDs.

NAND Configurations
Capacity 240GB 480GB 960GB
Raw NAND Capacity 256GiB 512GiB 1024GiB
Over-Provisioning 12.7% 12.7% 12.7%
# of NAND Packages 8 8 8
# of Die per Package 4x8GB 8x8GB 16x8GB

The endurance remains unchanged from the Extreme II despite the doubled warranty. While 80TB should be enough for most users, I still would have liked to see higher endurance with the longer warranty. I think that the 10-year warranty is there just to differentiate the drive for marketing reasons, because if the Extreme Pro is used in (for example) professional video editing for ten years, the 80TB rating, or about 22GB a day, will not be sufficient. It appears SanDisk is betting that its target users will either replace the drive within a few years or the endurance limit will be hit after the warranty runs out, meaning that the 10-year warranty may not actually add any concrete value to the end-user. Of course it can still offer peace of mind for replacement drives, but I would give more value to the endurance rating when comparing high-end SSDs. 

The Extreme Pro features a more advanced version of SanDisk's nCache SLC caching technology, called nCache Pro. The difference between the two is that the original nCache was mainly for the firmware and NAND mapping table caching for data integrity reasons (it's faster to write to the SLC portion in case of a sudden power loss) but the nCache Pro is more optimized for user data caching. SanDisk would not reveal the exact size of the SLC buffer but SanDisk did tell us that it is less than 1GB, which is quite small compared to Samsung's TurboWrite with up to 12GB of SLC cache. That makes me think that the purpose of nCache Pro is to act more as a DRAM-like cache instead of a performance buffer, because ultimately you want to store as little data as possible in the DRAM due to its volatility.

SanDisk still does DRAM caching too, but writes smaller than 4KB will be cached to the SLC cache. Most writes from the host are 4KB in size but those are also tricky for the SSD because page sizes are much larger than that (currently 16KB), so caching to the faster and more durable SLC portion makes sense for write-combining (i.e. wait for more small IOs to come in and then write them as 16KB to the MLC part). Traditionally write-combining is done in the DRAM but it is much safer to do that in the SLC buffer, because the data will still be safe after a power loss whereas with DRAM it would be gone. (Of course, a super capacitor design could protect data in the event of a power failure.)

Sadly there is no encryption support. I asked why in our meeting at Computex and SanDisk told me that because TCG Opal 2.0 is still relatively new, SanDisk wanted to roll it out with the lower volume X300s first and see how the market reacts. SanDisk argued that it did not see the need for that in the Extreme Pro because they view desktop users as the main market, although I disagreed because the popularity of mobile workstations and laptop-as-desktop setups is constantly increasing, such that good IO performance should not only be limited to desktop users. In addition, I think desktop users, especially in the enthusiast and professional crowd, would appreciate encryption support because the data they handle can be sensitive (such as in home clouds). Hopefully we will see proper encryption support in the next generation drive (or even better: through a firmware update) because it is a quite significant drawback in the Extreme Pro.

Test System

CPU Intel Core i5-2500K running at 3.3GHz (Turbo and 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

Performance Consistency & TRIM Validation
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  • ninjag - Thursday, June 19, 2014 - link

    Where can I find these 10000% washing machines? I have been tracking this market for years, and I am so tired of incremental 5% gains on washing machine silicon. WE WANT INNOVATION!!! Reply
  • brucek2 - Tuesday, June 17, 2014 - link

    Its discussions like this that make it hard for me to get a feel for whether it would matter to me or not.

    On the one hand, 162% sounds plenty substantial. I do not want to spend 162% more immersion-breaking time twiddling my thumbs waiting for the next level to load, let alone 162% more time to get through a compile so I can meet my next deadline.

    On the other hand, waiting 1/1,000th of a second does not actually sound any faster to me than waiting 1/4,000th of a second (these are the "average service times" in the benchmark), because I know my personal threshold for perceiving laggy response kicks in at around 0.1 seconds.

    So where does this leave me? Not sure really but in the case of doubt it probably goes to spend more. The extra $100-$200 of potential hardware savings would be eaten up quickly in my time to research it much further, to end up ordering & installing & migrating to another drive sooner than I otherwise would have, or if I really did end up twiddling my thumbs more.

    But never fear MyrddinE, I'm still not buying the 99.8% pure unicorn dust super connect audio cables.
    Reply
  • mickulty - Tuesday, June 17, 2014 - link

    There are plenty of use cases where every little helps - a 5% overclock, assuming linear scaling, would shave ~8.5 minutes off a 3 hour video transcoding task for example. Reply
  • UltraTech79 - Sunday, June 29, 2014 - link

    See but actual users do not do "blind tests" they do actual tests for their servers to see what is better. You dont need to feel the difference between 5 and 10 to know what number is higher. Reply
  • n13L5 - Thursday, December 3, 2015 - link

    In many cases, you are correct. But if you were just teetering near sufficient performance, a 5% performance increase to stay solidly just above 30 fps, the difference will suddenly become very obvious to perceive. Reply
  • UltraTech79 - Sunday, June 29, 2014 - link

    Yes. No one would notice...

    ...Except the sort of people that would read these kinds of articles. Your logic is a failure.
    Reply
  • vaayu64 - Monday, June 16, 2014 - link

    Thanks for a nice review. Do you know if Sandisk is going to release an mSata version of this ?
    Sadly, there isn't a good msata ssd > 240 GB capacity and with good performance consistency in the market right now....
    Regards
    Reply
  • 457R4LDR34DKN07 - Monday, June 16, 2014 - link

    I know what you mean because when I built my mITX I think the only drive I could find was the ocz nocti 128GB. If I was going to upgrade it I would go with a Samsung 840 evo but mSATA isn't worth investing into at this point with M.2 arrival IMO. Reply
  • vaayu64 - Monday, June 16, 2014 - link

    The 840 evo msata is without doubt a very nice ssd, but TRIM is not supported on that one. Reply
  • ijozic - Tuesday, June 17, 2014 - link

    Where did you get that (mis)information from? Reply

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