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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Jamor - Wednesday, March 18, 2009 - link
The best tech article I've ever read, and I've read a few.haze4peace - Wednesday, March 18, 2009 - link
Wow, excellent article and so much useful information in an easy to understand way. I have just recently been paying attention to SSDs and thanks to this article I am armed with the information to make the correct choice for my needs. Thanks AnandTech, its the deep and honest articles like these that keep me coming back for more.Alseki - Wednesday, March 18, 2009 - link
I just registered then simply to say, great article. Really informative and enjoyable to read.alexsch8 - Wednesday, March 18, 2009 - link
Anand,Thank you for this article, very informative.
Looking at the example you are giving with your self-manufactured SSD drive: If I save the DOC I use up a page. Based on what you are saying, if I make a change to that DOC, it would then be saved in the next page instead of overwriting the existing page? If that is true, then the File Allocation system (FAT or MFT) itself would contribute quite a bit to the 'filling up of pages' phenomena. Could you elaborate if the proposed file system for SSD addresses this?
Ytterbium - Wednesday, March 18, 2009 - link
Fantastic article, shame that the vendors blacklisted you for telling the truth and OCZ rock for working so hard to address issues.I'll be ordering my Intel SSD soon, I'll defintly consider the Summit when it comes out for my encoding rig as there sequental writes matter to me.
mindless1 - Wednesday, March 18, 2009 - link
Great even, but I've have to disagree with the significance of the passage that suggested the Indilinx controller makes data loss as bad on those SSD as on a conventional hard drive.The primary cause of data loss is mechanical or component failure, not power loss. If we want to consider power loss, it's not just the drive which is prone to lose data, the entire system memory suffers far more data loss than that.
Further, a sufficiently sized supercapacitor should keep the drive operating for a period of time beyond when the rest of the system would be operational, it could be sufficient for the controller to finish writing to flash all received data (or just use an UPS, that's what they're for?).
Second, I can't believe that OCZ only tests designs with HDTach and Atto, I think it more likely they knew of the problem but didn't expect anyone to find it so quickly, and felt the higher sequential speeds made it more marketable. This makes me feel that manufacturers, then online sellers should differentiate their drives with a standardized random read/write score.
What would be really nice is if the Indilinx based SSDs had an application available, similar to a HDD acoustic management bit changing app, that lets the owner set their own preference for IO versus sequential read performance.
gomakeit - Wednesday, March 18, 2009 - link
This is by far the BEST article on SSD I've ever read! Great job anand and yes I read every single word of it!MagicPants - Wednesday, March 18, 2009 - link
Don't they ever try using their own devices? One second of latency should slap any user in the face. It should be very easy for a manufacturer to build a system with their new technology put it in front of people and see what happens, but apparently they're not doing this.They wait for reviewers to do the work for them and then get upset when they find a problem.
What the manufacturers should be taking away from this article is:
1) Try your competitor's products
2) Try your own products
3) Try them in real life as opposed to synthetic tests
4) Compare everything you've tried and market the performance that matters
7Enigma - Thursday, March 19, 2009 - link
But that would make sense....and we know marketing rarely does.paulinus - Wednesday, March 18, 2009 - link
That art is great. Finally someone done ssd test's right, and said loud what we, customers, can get for that hefty pricetags.I've supposed that only choices are intel and new ocz's. Now I know, and big kudos for that.
Just need a bit more $$ for x25-m, it'll be ideal for heavy workstation use, and biggest vertex'll replace wd black in my aging 6910p :)