The SSD Anthology: Understanding SSDs and New Drives from OCZ
by Anand Lal Shimpi on March 18, 2009 12:00 AM EST- Posted in
- Storage
Disappointed, I went back to OCZ
OCZ was worried. The last time I reviewed one of their SSDs I was truthful about it, and it hurt their sales considerably. Customers were returning drives, and to OCZ’s credit, they stepped up and even accepted some returns themselves - something that most manufacturers wouldn’t have done. Regardless what they had told me, there was some admission of fault there. Those JMicron drives were nothing short of crap.
As soon as OCZ started getting word that I wasn’t pleased with Vertex, they went into a state of panic. These drives all do very well in synthetic HDD tests like HDTach and ATTO, that’s generally all they’re reviewed in, so that’s all they’re tested in. But now OCZ was hearing that the Vertex wasn’t passing some of my tests and they had no idea what it was failing or why.
I tend to do a good job of keeping what tests I run secret until the review is published, so there isn’t any unfair optimization. I purposefully introduce new tests to our performance suites to help keep manufacturers honest and optimizing for real world usage scenarios rather than specific benchmarks. OCZ had no idea what I was running, but they knew that the Vertex wasn’t doing well.
Summit on the other hand was performing just fine, but that’s an expensive drive. Vertex was supposed to be good, it should’ve been good, there’s no reason for it to be performing this poorly. I ran the infamous iometer test to see what was going on:
| Iometer 4KB Random Writes, IOqueue=1, 8GB sector space | IOs per second | MB/s | Average Latency | Maximum Latency |
| Original Pre-release OCZ Vertex | 20.7 | 0.08 MB/s | 48.2 ms | 484.5 ms |
How on earth is this acceptable at all? Average latency of 48.2ms and a maximum latency as bad as the Apex and G.Skill Titan drives? I’ve heard some SSD vendors dismiss the iometer results but let me caution you against that. What these numbers are telling us is that on average, when your OS goes to write a 4KB file somewhere on your drive, it’ll take nearly 50ms. That’s 4.5x longer than a 5400 RPM 2.5” notebook drive and that’s the average case. What part of that sounds acceptable? Anyone who tells you otherwise is delusional.
I thought for sure that the drive was broken and that we’d made no progress since last fall. But the drive hadn’t launched yet, while there were glowing reviews of it, no one had wasted any money. I wrote an email to Ryan Petersen, OCZ’s CEO. I described my findings and told him that while the Vertex’s performance was better than any of the JMicron solutions, it was unacceptable for anything other than perhaps extremely light, single-tasking usage.
I told him it sucked. He said that wasn’t fair. We argued over email but he came back and asked me what I needed to see to make the drive better.
I told him I’d need an average response time in the sub-1ms range and a max latency no worse than Intel’s 94ms. I didn’t think it would be possible. I was prepared for OCZ to hate me once more. He told me to give him a couple of days.
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Luddite - Friday, March 20, 2009 - link
So even with the TRIM command, when working with large files, say, in photoshop and saving multiple layers, the performance will stil drop off?proviewIT - Thursday, March 19, 2009 - link
I bought a Vertex 120GB and it is NOT working on my Nvidia chipsets motherboard. Anyone met the same problem? I tried intel chipsets motherboard and seems ok.I used HDtach to test the read/write performance 4 days ago, wow, it was amazing. 160MB/s in write. But today I felt it slower and used HDtach to test again, it downs to single digit MB per second. Can I recover it or I need to return it?
kmmatney - Thursday, March 19, 2009 - link
Based on the results and price, I would say that the OCZ Vertex deserves a Editor's choice of some sort (Gold, Silver)...Tattered87 - Thursday, March 19, 2009 - link
While I must admit I skipped over some of the more technical bits where SSD was explained in detail, I read the summaries and I've gotta admit this article was extremely helpful. I've been wanting to get one of these for a long time now but they've seemed too infantile in technological terms to put such a hefty investment in, until now.After reading about OCZ's response to you and how they've stepped it up and are willing to cut unimportant statistics in favor of lower latencies, I actually decided to purchase one myself. Figured I might as well show my appreciation to OCZ by grabbing up a 60GB SSD, not to mention it looks like it's by far the best purchase I can make SSD-wise for $200.
Thanks for the awesome article, was a fun read, that's for sure.
bsoft16384 - Thursday, March 19, 2009 - link
Anand, I don't want to sound too negative in my comments. While I wouldn't call them unusable, there's no doubt that the random write performance of the JMicron SSDs sucks. I'm glad that you're actually running random I/O tests when so many other websites just run HDTune and call it a day.That X25-M for $340 is looking mighty tempting, though.
MrSpadge - Thursday, March 19, 2009 - link
Hi,first: great article, thanks to Anand and OCZ!
Something crossed my mind when I saw the firmware-based trade-off between random writes and sequential transfer rates: couldn't that be adjusted dynamically to get the best of both worlds? Default to the current behaviour but switch into something resembling te old one when extensive sequential transfers are detected?
Of course this neccesiates that the processor would be able to handle additional load and that the firmware changes don't involve permanent changes in the organization of the data.
Maybe the OCZ-Team already thought about this and maybe nobody's going to read this post, buried deep within the comments..
MrS
Per Hansson - Thursday, March 19, 2009 - link
Great work on the review AnandI really enjoyed reading it and learning from it
Will there be any tests of the old timers like Mtron etc?
tomoyo - Thursday, March 19, 2009 - link
That was kind of strange to me too. But I assume Anand really means the desktop market, not the server storage/business market. Since it's highly doubtful that the general consumer will spend many times as much money for 15k SAS drives.Gary Key - Thursday, March 19, 2009 - link
The intent was based it being the fastest for a consumer based desktop drive, the text has been updated to reflect that fact.tomoyo - Thursday, March 19, 2009 - link
I've always been someone who wants real clarify and truth to the information on the internet. That's a problem because probably 90% of things are not. But Anand is one man I feel a lot of trust for because of great and complete articles such as this. This is truly the first time that I feel like I really understand what goes into ssd performance and why it can be good or bad. Thank you so much for being the most inciteful voice in the hardware community. And keep fighting those damn manufacturers who are scared of the facts getting in the way of their 200MB/s marketing bs.