One thing AMD has taught me is that you can never beat Intel at its own game. Simply trying to do what Intel does will leave you confined to whatever low margin market Intel deems too unattractive to pursue. It’s exactly why AMD’s most successful CPU architectures are those that implement features that Intel doesn’t have today, but perhaps will have in a few years. Competing isn’t enough, you must innovate. Trying to approach the same problem in the same way but somehow do it better doesn’t work well when your competition makes $9B a quarter.

We saw this in the SSD space as well. In the year since Intel’s X25-M arrived, the best we’ve seen is a controller that can sort-of do what Intel’s can just at a cheaper price. Even then, the cost savings aren’t that great because Intel gets great NAND pricing. We need companies like Indilinx to put cost pressure on Intel, but we also need the equivalent of an AMD. A company that can put technological pressure on Intel.

That company, at least today, is SandForce. And its disciple? OCZ. Yep, they’re back.

Why I Hate New SSDs

I’ll admit, I haven’t really been looking forward to this day. Around the time when OCZ and Indilinx finally got their controller and firmware to acceptable levels, OCZ CMO Alex Mei dropped a bombshell on me - OCZ’s Vertex 2 would use a new controller by a company I’d never heard of. Great.

You may remember my back and forth with OCZ CEO Ryan Petersen about the first incarnation of the Vertex drive before it was released. Needless to say, what I wrote in the SSD Anthology was an abridged (and nicer) version of the back and forth that went on in the months prior to that product launch. After the whole JMicron fiasco, I don’t trust these SSD makers or controller manufacturers to deliver products that are actually good.


Aw, sweet. You'd never hurt me would you?

Which means that I’ve got to approach every new drive and every new controller with the assumption that it’s either going to somehow suck, or lose your data. And I need to figure out how. Synonyms for daunting should be popping into your heads now.

Ultimately, the task of putting these drives to the test falls on the heads of you all - the early adopters. It’s only after we collectively put these drives through hundreds and thousands of hours of real world usage that we can determine whether or not they’re sponge-worthy. Even Intel managed to screw up two firmware releases and they do more in-house validation than any company I’ve ever worked with. The bugs of course never appeared in my testing, but only in the field in the hands of paying customers. I hate that it has to be this way, but we live in the wild west of solid state storage. It’ll be a while before you can embrace any new product with confidence.

And it only gets more complicated from here on out. The old JMicron drives were easy to cast aside. They behaved like jerks when you tried to use them. Now the true difference between SSDs rears its head after months or years of use.

I say that because unlike my first experience with OCZ’s Vertex, the Vertex 2 did not disappoint. Or to put it more directly: it’s the first drive I’ve seen that’s actually better than Intel’s X25-M G2.

If you haven't read any of our previous SSD articles, I'd suggest brushing up on The Relapse before moving on. The background will help.

Enter the SandForce
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  • Anand Lal Shimpi - Friday, January 01, 2010 - link

    Correct. Highly Random and highly compressed data will not work well with SandForce's current algorithm. Less than 25% of the writes you'll see on a typical desktop machine are random writes, even then they aren't random over 100% of the LBA space. I'm not sure how well the technology works for highly random server workloads (SF claims it's great), but for the desktop user it appears to be perfect.

    Take care,
    Anand
    Reply
  • shawkie - Friday, January 01, 2010 - link

    Thinking about this further I've come to the conclusion that the files must be divided into small blocks that are compressed independently. Firstly because the disk doesn't know about files (only sectors) and secondly because its the only way you could modify a small part of a compressed file quickly. I don't think 512 bytes would be big enough to acheive respectable compression ratios so I think 4KB is more likely. This might explain why Seagate are pushing to make 4KB the smallest addressable unit for storage devices. So then they take each 4KB block, compress it, and write it to the next available space in flash. If they use 64 bit pointers to store the location of each 4KB block they could easily address the entire space with single-bit granularity. Of course, every overwrite will result in a bit of irregularly sized free space. They could then just wait for a bit of compressed data that happens to fit perfectly or implement some kind of free space consolidation or a combination. I'm starting to come around to the idea. Reply
  • shawkie - Friday, January 01, 2010 - link

    Apologies to Anand, I completely missed the page titled "SandForce's Achilles' Heel". I do think there are some scenarios that still need testing though. What happens when a small modification has to be made to a large file that the drive has decided to compress? Not an easy thing to benchmark but something I can imagine might apply when editing uncompressed audio files or some video files. The other question is what happens when the disk is made dirty by overwriting several times using a random write pattern and random data. What is the sequential write speed like after that? Reply
  • lesherm - Friday, January 01, 2010 - link

    with a Seinfeld reference. Reply
  • LTG - Friday, January 01, 2010 - link

    Definitely the only one with a Seinfeld and a Metallica and a StarWars reference :).


    Sponge Worthy
    Enter the Sandforce
    Use the Sandforce
    Reply
  • GullLars - Thursday, December 31, 2009 - link

    It seems anand has a problem with identifying the 4KB random performance of the drives.

    Intel x25-M has time and time again been shown to deliver 120MB/s or more 4KB random read bandwidth. x25-E delivers in the area of 150MB/s random read and 200MB/s of random write at 4KB packet sizes for queue depth of 10 and above.

    I do not know if the problem is due to testing not being done in AHCI/RAID mode, or if it is because of a queue depth lower than number of internal flash channels, but these numbers are purely WRONG and misrepresentative. I probably shouldn't post while drunk :P but this upsets me enough to disregard that.

    Anandtech is IMO a site too good to post nonsensical data like this, pleese fix it ASAP. If you choose to sensor my post after fixing it, pleese mail me notifying me of it in case i don't remmeber posting.
    Reply
  • Anand Lal Shimpi - Friday, January 01, 2010 - link

    My 4KB read/write tests are run with a queue depth of 3 to represent a desktop usage scenario. I can get much higher numbers out of the X25-M at higher queue depths but then these tests stop being useful for desktop/notebook users. I may add server-like iometer workloads in the future though.

    All of our testing is done in non-member RAID mode.

    Take care,
    Anand
    Reply
  • GullLars - Friday, January 01, 2010 - link

    Thank you for the response, but i still feel the need to point out that posting 4KB random numbers for queue depth 3 should be explicitly pointed out, as this only utilizes less than 1/3 of the flash channels in the x25-M. Here is a graph i made of the 4KB random read IOPS numbers of an x25-M by queue depth: http://www.diskusjon.no/index.php?act=attach&t...">http://www.diskusjon.no/index.php?act=attach&t...
    As shown in this graph, the performance scales well up to a queue depth of about 12, where the 10 internal channels get saturated with requests.

    A queue depth of 3 may be representative for average light load running windows, but during operations like launching programs, booting windows, or certain operations whitin programs that read database listings, the momentary queue depths often spike to 16-64, and it is in theese circumstances you really feel the IOPS performance of a drive. This is one of the reasons why x25-M beats the competition in the application launch test in PCmark vantage despite having the same IOPS performance at queue depths 1-4 and about the same sequential performance.

    The sandforce SF-1500 controller is rated for 30.000 4KB random IOPS, 120MB/s. In order to reach these read performance numbers with MLC flash, you need at least 6 channels, with corresponding outstanding IO's to make use of them. Then you also need to take into account controller overhead. The SF-1500 controller has 16 channels, and the SF-1200 controller has 8 channels.
    To test IOPS performance of a drive (not enterpreted for usage but raw numbers), outstanding IOs should be at least equal to number of channels.
    Reply
  • Anand Lal Shimpi - Friday, January 01, 2010 - link

    I'm not sure I agree with you here:

    "A queue depth of 3 may be representative for average light load running windows, but during operations like launching programs, booting windows, or certain operations whitin programs that read database listings, the momentary queue depths often spike to 16-64,"

    I did a lot of tests before arriving at the queue depth of 3 and found that even in the most ridiculous desktop usage scenarios we never saw anything in the double digits. It didn't matter whether you were launching programs in parallel or doing a lot of file copies while you were interacting with apps. Even our heavy storage bench test had an average queue depth below 4.

    Take care,
    Anand
    Reply
  • GullLars - Saturday, January 02, 2010 - link

    I'm not out to be difficult here, so i will let it be after this, but what i and a few others who have been doing SSD benchmarking for about a year now have found using the windows performance monitor indicates Queue Depth spikes in the area of 16-64 outstanding IO's when launching apps, and certain other interactions with apps that cause reading of many database entries.

    Copying files will only create 1 outstanding sequential IO-queue, and does not contribute significantly to the momentary queue depth during short high loads.

    Scanning for viruses may contribute more to the queue depth, but i have not tested it this far.

    At a queue depth of 1-4 for purely reads, there is little difference between JMicron, Indilinx, Samsung, Mtron, and Intel based SSDs, and the difference seen in PCmark Vantage applauch test and real world tests of "launch scripts" (a script launching all programs installed on the computer simultaneously) also indicate there is a notable difference. Some of this may be caused by different random write performance and sequential read, but queue depths above 4 in bursts help explain why x25-M with the 10-channel design beats the competing 4-channel controllers in this type of workload even when sequential read is about the same.

    I also like to think Intel didn't make a complex 10-channel "M" drive optimized for 4KB random IOPS targeted at consumers only to win in benchmarks. If the queue depth truly never went above 3-5, even when counting bursts, there would have been wasted a ridiculus amount of effort and resources in making the x25-M, as a 4-channel drive would be a lot cheaper to develop and produce.


    Thanks for taking the time to reply to my posts, and i hope you know i value the SSD articles posted on this site. My only concern has been the queue depths used for performance rating, and a concern for the future is that the current setup does not forward TRIM to drives supporting it.
    Reply

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