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
Random Read/Write Performance
Arguably much more important to any PC user than sequential read/write performance is random access performance. It's not often that you're writing large files sequentially to your disk, but you do encounter tons of small file reads/writes as you use your PC.
To measure random read/write performance I created an iometer script that peppered the drive with random requests, with an IO queue depth of 3 (to add some multitasking spice to the test). The write test was performed over an 8GB range on the drive, while the read test was performed across the whole drive. I ran the test for 3 minutes.
The three hard drives all posted scores below 1MB/s and thus aren't visible on our graph above. This is where SSDs shine and no hard drive, regardless of how many you RAID together, can come close.
The two Intel drives top the charts and maintain a huge lead. The OCZ Vertex actually beats out the more expensive (and unreleased) Summit drive with a respectable 32MB/s transfer rate here. Note that the Vertex is also faster than last year's Samsung SLC drive that everyone was selling for $1000. Even the JMicron drives do just fine here.
If we look at latency instead of transfer rate it helps put things in perspective:
Read latencies for hard drives have always been measured in several ms, but every single SSD here manages to complete random reads in less than 1ms under load.
Random write speed is where we can thin the SSD flock:
Only the Intel drives and to an extent, the OCZ Vertex, post numbers visible on this scale. Let's go to a table to see everything in greater detail:
| 4KB Random Write Speed | |
| Intel X25-E | 31.7 MB/s |
| Intel X25-M | 23.1 MB/s |
| JMicron JMF602B MLC | 0.02 MB/s |
| JMicron JMF602Bx2 MLC | 0.03 MB/s |
| OCZ Summit | 0.77 MB/s |
| OCZ Vertex | 2.41 MB/s |
| Samsung SLC | 0.53 MB/s |
| Seagate Momentus 5400.6 | 0.81 MB/s |
| Western Digital Caviar SE16 | 1.26 MB/s |
| Western Digital VelociRaptor | 1.63 MB/s |
Every single drive other than the Intel X25-E, X25-M and OCZ's Vertex is slower than the 2.5" Seagate Momentus 5400.6 hard drive in this test. The Vertex, thanks to OCZ's tweaks, is now 48% faster than the VelociRaptor.
The Intel drives are of course architected for the type of performance needed on a desktop/notebook and thus they deliver very high random write performance.
Random write performance is merely one corner of the performance world. A drive needs good sequential read, sequential write, random read and random write performance. The fatal mistake is that most vendors ignore random write performance and simply try to post the best sequential read/write speeds; doing so simply produces a drive that's undesirable.
While the Vertex is slower than Intel's X25-M, it's also about half the price per GB. And note that the Vertex is still 48% faster than the VelociRaptor here, and multiple times faster in the other tests.
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GlItCh017 - Wednesday, March 18, 2009 - link
I just wanted to comment that the backstory portion to this article is simply the most interesting part to an article (or almost even an article inside the main article). On top of that, it is easily the most interesting article I have ever read simply because of that section. Really really must say that I enjoyed reading it!radguy - Wednesday, March 18, 2009 - link
I have been waiting for this one for a while and it was very informative. Thank you very much for it. I did pick up one of the patriot warp drives for my netbook. I was really happy until I installed avg free. So not running an antivirus on it anymore but I have drive image backup incase it goes bad. Overall pretty happy as it was only 80 bucks if I get my mir.I think I'm going to wait until windows 7 till I upgrade my primary desktop. 2 of those vertexs in raid 0 would be sweet though.
sleepeeg3 - Wednesday, March 18, 2009 - link
They were one of the first SSDs you reviewed and they use their own controller. How does their random write performance compare to everything else out now?These reviews made me totally reassess the purchase of the two Samsungs I bought. I had no idea the random writes on the Samsung drives were so bad. Other reviews show the Samsung drives doing better or at least near the X25-M in write tests: http://www.techreport.com/articles.x/15433/6">http://www.techreport.com/articles.x/15433/6 However, those tests probably would have been somewhat sequential.
nubie - Wednesday, March 18, 2009 - link
Grammatically awkward sentence on Page 21:"so if you own one of these drives - you owned a fixed version."
The tense is incorrect (own/owned). I think "own a fixed version" is still awkward, perhaps "you have the fixed version", also the "so" may be superfluous. You can replace the ", so if" with a "; if". Here is how I might re-write the sentence:
"The old firmware never shipped thanks to OCZ's quick acting; if you own one of these drives - you have a fixed version."
(I am not an expert, so feel free to correct me if I am wrong.)
Awesome article btw, thanks for setting me straight on SSD, I have been steering clear of them. I hope soon you can review SSD's and most are good to excellent. :)
Flyboy27 - Wednesday, March 18, 2009 - link
This article has answered every question I've had regarding SSDs recently. Thanks Anand!Flyboy27 - Wednesday, March 18, 2009 - link
If a 120gb Vertex was around $250 I would get one yesterday. I suppose I can wait though.7Enigma - Thursday, March 19, 2009 - link
For me, 2 60's or 2 80's for around that price and I'm sold. Want the Raid0.kgwagner - Wednesday, March 18, 2009 - link
I almost didn't read this article, as everybody and their brother seems to want to explain SSDs these days and most of the articles aren't much more than glorified press releases. But, this one truly took the drives to task and presented some valid information and explanations about the state of the art and where it needs to go. Kudos, Anand. Awesome show. Good job.Mr Perfect - Wednesday, March 18, 2009 - link
"Needless to say, there was some definite fallout from that review. I’m used to negative manufacturer response after a GPU review, but I’m always a bit surprised when it happens in any other segment."Obviously you can't make a business out of irritating manufacturers, but when there really are issues, the readers want to know about them. After all, that's why we come here!
gwolfman - Wednesday, March 18, 2009 - link
You own Anand. Keep up the good work. I've seen you cited from many sites about the work you've done, in particular with SSDs. Best article I've read in months!