Capacities and Hella Overprovisioning

SandForce’s attention is focused on the enterprise, which makes sense given that’s where the money is. As a result, its drives are aimed at enterprise capacity points. The first products you’ll see based on SandForce will be 50, 100, 200 and 400GB capacity points. That’s in GB, in terms of user space it’s 46.6 GiB, 93.1GiB, 186.3GiB and 372.5GiB.

On top of the ~7% spare area you get from the GB to GiB conversion, SandForce specifies an additional 20% flash be set aside for spare area. The table below sums up the relationship between total flash, advertised capacity and user capacity on these four drives:

Advertised Capacity Total Flash User Space
50GB 64GB 46.6GB
100GB 128GB 93.1GB
200GB 256GB 186.3GB
400GB 512GB 372.5GB

 

This is more spare area than even Intel sets aside on its enterprise X25-E drive. It makes sense when you consider that SandForce does have to store more data in its spare area (all of that DuraWrite and RAISE redundancy stuff).

Dedicating almost a third of the flash capacity to spare area is bound to improve performance, but also seriously screw up costs. That doesn’t really matter for the enterprise market (who’s going to complain about a $1500 drive vs. a $1000 drive?), but for the client space it’s a much bigger problem. Desktop and notebook buyers are much more price sensitive. This is where SandForce’s partners will need to use cheaper/lower grade NAND flash to stay competitive, at least in the client space. Let’s hope SandForce’s redundancy and error correction technology actually works.

There’s another solution for client drives. We’re getting these odd capacity points today because the majority of SF’s work was on enterprise technology, the client version of the firmware with less spare area is just further behind. We’ll eventually see 60GB, 120GB, 240GB and 480GB drives. Consult the helpful table below for the lowdown:

Advertised Capacity Total Flash User Space
60GB 64GB 55.9GB
120GB 128GB 111.8GB
240GB 256GB 223.5GB
480GB 512GB 447.0GB

 

That’s nearly 13% spare area on a consumer drive! Almost twice what Intel sets aside. SandForce believes this is the unavoidable direction all SSDs are headed in. Intel would definitely benefit from nearly twice the spare area, but how much more you willing to pay for a faster SSD? It would seem that SandForce’s conclusion only works if you can lower the cost of flash (possibly by going with cheaper NAND).

Controlling Costs with no DRAM and Cheaper Flash Inside the Vertex 2 Pro
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  • Shark321 - Monday, January 25, 2010 - link

    Kingston has released a new SSD series (V+) with the Samsung controller. I hope Anandtech will review it soon. Other sites are not reliable, as they test only sequential read/writes. Reply
  • Bobchang - Wednesday, January 20, 2010 - link

    Great Article!
    it's awesome to have new feature SSD and I like the performance
    but, regarding your test, I don't get the same random read performance from IOMeter.

    Can you let me know what version of IOMeter and configuration you used for the result? I never get more than around 6000 IOPS.
    Reply
  • AnnonymousCoward - Wednesday, January 13, 2010 - link

    Anand,

    Your SSD benchmarking strategy has a big problem: there are zero real-world-applicable comparison data. IOPS and PCMark are stupid. For video cards do you look at IOPS or FLOPS, or do you look at what matters in the real world: framerate?

    As I said in my post here (http://tinyurl.com/yljqxjg)">http://tinyurl.com/yljqxjg), you need to simply measure time. I think this list is an excellent starting point, for what to measure to compare hard drives:

    1. Boot time
    2. Time to launch applications
    _a) Firefox
    _b) Google Earth
    _c) Photoshop
    3. Time to open huge files
    _a) .doc
    _b) .xls
    _c) .pdf
    _d) .psd
    4. Game framerates
    _a) minimum
    _b) average
    5. Time to copy files to & from the drive
    _a) 3000 200kB files
    _b) 200 4MB files
    _c) 1 2GB file
    6. Other application-specific tasks

    What your current strategy lacks is the element of "significance"; is the performance difference between drives significant or insignificant? Does the SandForce cost twice as much as the others and launch applications just 0.2s faster? Let's say I currently don't own an SSD: I would sure like to know that an HDD takes 15s at some task, whereas the Vertex takes 7.1s, the Intel takes 7.0s, and the SF takes 6.9! Then my purchase decision would be entirely based on price! The current benchmarks leave me in the dark regarding this.
    Reply
  • rifleman2 - Thursday, January 14, 2010 - link

    I think the point made is a good one for an additional data point for the decision buying process. Keep all the great benchmarking data in the article and just add a couple of time measurements so, people can get a feel for how the benchmark numbers translate to time waiting in the real world which is what everyone really wants to know at the end of the day.

    Also, Anand did you fill the drive to its full capacity with already compressed data and if not, then what happens to performance and reliability when the drive is filled up with already compressed data. From your report it doesn't appear to have enough spare flash capacity to handle a worse case 1:1 ratio and still get decent performance or a endurance lifetime that is acceptable.
    Reply
  • AnnonymousCoward - Friday, January 15, 2010 - link

    Real world top-level data should be the primary focus and not just "an additional data point".

    This old article could not be a better example:
    http://tinyurl.com/yamfwmg">http://tinyurl.com/yamfwmg

    In IOPS, RAID0 was 20-38% faster! Then the loading *time* comparison had RAID0 giving equal and slightly worse performance! Anand concluded, "Bottom line: RAID-0 arrays will win you just about any benchmark, but they'll deliver virtually nothing more than that for real world desktop performance."
    Reply
  • AnnonymousCoward - Friday, January 15, 2010 - link

    Icing on the cake is this latest Vertex 2 drive, where IOPS don't equal bandwidth.

    It doesn't make sense to not measure time. Otherwise what you get is inaccurate results to real usage, and no grasp of how significant differences are.
    Reply
  • jabberwolf - Friday, August 27, 2010 - link

    The better way to test rather then hopping on your mac and thinking thats the end-all be-all of the world is to throw this drive into a server, vmware or xenserver... and create multiple VD sessions.

    1- see how many you can boot up at the same time and run heavy loads.
    The boot ups will take the most IOPS.

    Sorry but IOPS do matter so very much in the business world.

    For stand alone drives, your read writes will be what your are looking for.
    Reply
  • Wwhat - Wednesday, January 06, 2010 - link

    This is all great, finally a company that realizes the current SSD's are too cheap and have too much capacity and that people have too much money.

    Oh wait..
    Reply
  • Wwhat - Wednesday, January 06, 2010 - link

    Double post was caused by anadtech saying something had gone wrong, prompting me to retry. Reply
  • Wwhat - Wednesday, January 06, 2010 - link

    This is all great, finally a company that realizes the current SSD's are too cheap and have too much capacity and that people have too much money.

    Oh wait..
    Reply

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