The OCZ RevoDrive 3 X2 Preview: Second-Gen SandForce Goes PCIe

128 KB Sequential Performance

SSD manufacturers often want to stress random performance because it's a clear case where they decimate hard drive manufacturers. Sequential performance is a little different, but still represents an important aspect of performance to examine. Think about how you read and write data.

But how pervasive is sequential performance for the average user? Take a look at the graph below; it shows the distribution of all the seek distances from one of our traces.

The first thing you'll notice is that there's a preponderance of activity zero sectors away, which means that my trace is made mostly of back-to-back requests, or sequential I/O. If the trace was 100% random, none of the accesses should be zero sectors away. But that's the opposite of what we're seeing here. Why is this?

Much of what you read and write to your storage on a day-to-day basis is random in nature. But over the course of days and weeks, the read-modify-erase-write cycle has a significant effect on the sequential and random I/O balance. Remember that SSDs have this dynamic where writing occurs at the page level, but erasing has to occur at the block level (blocks are made up of multiple pages). This is where garbage collection comes into play.

When you write random data, the block containing that data is going to accumulate invalid pages as you delete information, and if you have a block with a lot of pages that need to be moved, the SSD controller rewrites them sequentially. So, when you read back that information, you do so sequentially, even though it was originally written randomly. Eventually, over time, you see random reads turn into sequential reads. Note that this isn't a wholesale transition. How much of a migration depends on firmware and the SSD controller's architecture.

When you're dealing with sequential transfers, 128 KB is ultimately the most important transfer size. It is to sequential measurements what 4 KB blocks are to random performance.

In sequential transfers, the RevoDrive 3 X2 reigns king. It simply smokes the competition. We talking about more than 500 MB/s in both read and writes. Its closest competitors are at least 175 MB/s behind. That's an amazing 35% difference.

Before you're completely shocked by the low scores, remember that we're testing steady state performance. This changes the behavior of the SSD. Remember also that OCZ's drives center on SandForce controllers, which are architected to achieve their best possible performance when they're operating on compressible data. In the real world, that's actually a pretty realistic expectation. Completely random/incompressible data is fairly rare. It includes stuff like encrypted, precompressed files or encoded video data.

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37 comments
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  • reyshan
    YoT!damn fast ssd and damn expensive ssd. might buy one 5 years from now(pci-e kind).
    3
  • KingArcher
    Wish I had won a lottery :)
    So that I could afford me some drives like these.
    2
  • Why_Me
    omg this drive is fast! But way out of my budget :(
    6
  • warmon6
    Quote:
    It's not a business-class product. It's for the power user who is able to tax it using the right workload. If you're not one of those folks, the RevoDrive 3 X2 is seriously overkill.


    OVERKILL?!?!

    Nothing is overkill in the computer arena in terms of performance. :p

    Just the price can be over kill. o.0
    4
  • julius 85
    Just the price can be over kill. o.0

    For me the price is a bottleneck :)
    7
  • ElectroGoofy
    Dear Santa...
    7
  • acku
    Santa is going to need a bigger expense account... :)

    Personally, I'm hoping that OCZ adds TRIM prior to September.

    Cheers,
    Andrew Ku
    TomsHardware.com
    2
  • chefboyeb
    Jesus!
    -1
  • greenrider02
    I saw defense of the Vertex 3's occasional low numbers, but no mention of the solid (and sometimes better) performance that the cheaper and more miserly Crucial m4 showed throughout your tests.

    Perhaps you have some bias towards the Vertex 3 that needs reconsideration?

    Other than that, $700 seems like a fair price when considering the performace difference, especially if utilized properly, for instance as a high traffic web/corporate server
    -2
  • acku
    greenrider02I saw defense of the Vertex 3's occasional low numbers, but no mention of the solid (and sometimes better) performance that the cheaper and more miserly Crucial m4 showed throughout your tests.Perhaps you have some bias towards the Vertex 3 that needs reconsideration?Other than that, $700 seems like a fair price when considering the performace difference, especially if utilized properly, for instance as a high traffic web/corporate server


    If you read the first page then you know that I give a nod to Vertex 3s as the fastest MLC based 2.5" SSD. I consider that plenty of love. :).

    We'll discuss the lower capacity m4s in another article. FYI, I suggest that you read page 5 and page 6. We are not testing FOB. We are testing steady state. That's part of the reason the SF-based drives are behaving differently with incompressible data.

    On your second point, this is in no way targeted toward an enterprise environment (that's what Z-drives are for). There is no redundancy in the array if a single SF controller fails. The whole card is a dud afterward. You can add higher level redundancy, but enterprise customers have so far been nervous on SandForce products. Plus, there's a general preference for hardware vs. software redundancy. (That's them talking not me). Overall, this makes it unacceptable for any enterprise class workload.
    0
  • Supertrek32
    You know, almost any application that would actually benefit from these speeds won't be very effective on these drives. Why? Not enough storage space.

    It's like having a car that can do 300 miles an hour, but can only carry enough fuel to go 20 miles. Does it have a niche? Yeah. Is it practical? Not really.
    0
  • cronos177
    In a couple of years I see them for like 1/2 the price. ONLY worth it for people who earn their paychecks based on the ability to finish task faster. that's the sole purpose at the moment.
    0
  • guzami77
    I have the X2 100GB... im not that impressed. The speed isnt meeting specs, and other hardware/software doesnt always like a PCIe(non-standard) hard drive. Also dont forget you cant overclock your PCIe voltage with one of these...
    1
  • acku
    guzami77I have the X2 100GB... im not that impressed. The speed isnt meeting specs, and other hardware/software doesnt always like a PCIe(non-standard) hard drive. Also dont forget you cant overclock your PCIe voltage with one of these...


    I really recommend that you update the firmware. I do notice a speed difference. If you've seen our compressible benchmarks, then you know that over time the RevoDrive X2 can perform poorly. The lack of TRIM doesn't help. :(
    0
  • chefboyeb
    The prices are too steep tho...
    1
  • compton
    This is an excellent exploration of SSD performance in general. Without the benefit of storage benches I myself have been wondering why one of my SSDs seems so much faster that the other, when it seems at face value that the answer should be clear.

    As far as OCZ goes, people who can benefit from this drive are a small group, but I'm not exactly sure who that is. Sure, its fantastically fast, and faster is better, but most people would tragically under-utilize a product like this. Since it's clearly not for enterprise use, I just have to guess what a typical user looks like for this device. Is it the high end media creation freelancer? Someone who makes their bones with Photoshop? Who knows? I want one, even though I'd clearly be better served by a more pedestrian drive. It's clearly destined for the "Cool Wall".
    0
  • acku
    Ok. I feel like I need to clear up some confusion. Some sites are reporting TRIM support and we're saying there is no TRIM support.

    The RevoDrive 3 X2 has hardware support for TRIM through VCA 2.0. This much is true, but you can't use TRIM because of a software problem. As for why?

    OCZ has a problem getting the TRIM command to the RevoDrive 3 X2, because it uses SCSI commands over PCIe, hence StorPort SCSI drivers. The TRIM command is out of the question because it's technically part of SATA. The only alternative is Unmap, which is to SCSI what TRIM is to SATA. Unfortunately, Windows does not support Unmap as part of its native driver stack. Furthermore, TRIM commands are only issued by Windows 7 when you empty the Recycle Bin, but you must have your SSD set to AHCI (part of SATA). Obviously this different from SCSI. So effectively no TRIM. :(

    We have been in contact with the Windows driver team and OCZ, so we know that a fix is being explored. If it materializes, that's another matter....

    (RevoDrive and RevoDrive X2 don't don't support TRIM at the hardware level, so the issue is moot for them.)

    Cheers,
    Andrew Ku
    TomsHardware.com
    2
  • Niva
    Ideal user would run massive databases that need tons of accesses all the time. Are there drivers for linux for this? Small business server with the right usage will make this worth it. Also the 'trim' issue should be a non-issue under linux whereas win 7 apparently doesn't include the unmap command.
    2
  • christop
    Crazy fast!!!
    2
  • warmon6
    __-_-_-__$700?! wow that's a nice price. Though performance @1.25gbps is kind of low for a pci-e solution. there's already on the market +2gbps. anyway those cost +$7000!I'm going to wait and see if there's any defect with this ssd's...


    Where you get Gbps (= Gigabits) from? ;) http://en.wikipedia.org/wiki/Data_rate_units#Suffix:_b_vs_B

    Were talking about GBps (Gigabytes). :p
    0