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
Simulating a Used Drive
Since SSD performance degrades over time, it’s important to not only look at how well these drives perform new - but also the worst they’d perform over their lifetime. In order to do so we’d need a repeatable way of “seasoning” a drive to reduce its performance to the worst it could possibly get. The most realistic worst-case scenario is one where every single block on the drive is full of data. If a secure erase wipes all LBAs, that’s the best place to start. To simulate a well seasoned drive I first secure erased the drive.
After the secure erase, I used iometer to write one contiguous file across the disk - filling up the entire drive with 128KB blocks. In the case of the 80GB Intel X25-M, that’s 74.5GB of data on the drive before I run a single benchmark. The spare area is left untouched.
Next, I take my test image and I restore it onto the partition with a sector by sector copy. The sequential file write made sure that data is stored in every page of the SSD, the test image restore adds a twist of randomness (and realism) to the data.
There are other ways to produce a drive in its well-used state, but this ends up being the most consistent and repeatable. To confirm that my little simulation does indeed produce a realistically worn drive I ran PCMark on three different drives: 1) a freshly secure-erased Intel X25-M, 2) an Intel X25-M setup using the method I just described and 3) the Intel X25-M used in my CPU testbed that has been through hundreds of SYSMark runs.
The benchmark of choice is PCMark Vantage; it simulates the real world better than most drive benchmarks. The results are below:
| Intel X25-M State | PCMark Vantage Overall Test | PCMark Vantage HDD Test |
| Fresh Secure Erase | 11902 | 29879 |
| Simulated Used Drive | 11536 | 23252 |
| Actual Testbed Used Drive | 11140 | 23438 |
The secure erased system loses about 3% of its overall performance and 22% of its hard drive specific performance compared to my testbed drive. The seasoning method I described above produces a drive with nearly identical drops in performance.
The method appears to be sound.
Now that we have a way of simulating a used drive, let’s see how the contestants fared.
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VaultDweller - Wednesday, March 18, 2009 - link
I love it when people critique someone's critique of grammar... and get it wrong.It's an SSD, not a SSD.
gwolfman - Wednesday, March 18, 2009 - link
lolzsidex - Wednesday, March 18, 2009 - link
I would like to know the firmware version of Vertex used in your review. To me sounds the old 0112kensiko - Wednesday, March 18, 2009 - link
Yes that is important to know.I'm sure this is not done with the latest firmware available which is 1199. This version got better performance.
Firmware 1275 is coming also.
Anand, will you update your benchmarks with the latest firmware?
If not, then the benchmarks are obsolete.
Anand Lal Shimpi - Wednesday, March 18, 2009 - link
I tested with the shipping firmware for this article (0122). I've been playing around with 1199 in the lab and will most likely have an update in a couple of weeks once I've done a thorough evaluation of it. By then I should also have the final version of the new Samsung drive and maybe even some other interesting things.For now, I've got to get to work on the new Mac Pro and the updated Ion article :) I need a small break from SSDs por favor :)
Take care,
Anand
VaultDweller - Wednesday, March 18, 2009 - link
Awww, don't you have some underlings to do your SSD-related will?Would love to see an update, and would love to see Corsair's SSD drive tested as well (it's based on Samsung's last generation MLC controller, and doesn't seem to emphasize sequential like the Summit does).
Anand Lal Shimpi - Wednesday, March 18, 2009 - link
I will do an update on the new firmware, I just want to do it right so it'll take some time :)I'll put in a request for the Corsair drive as well :)
-A
Slash3 - Wednesday, March 18, 2009 - link
Page 29: "Not all applications will launch faster than a VelociRaptor on a SSD, but let's not forget that the VelociRaptor is the world's fastest hard drive."Really? What about the nice and speedy enterprise-level 15k SAS/SCSI drives everyone neglects to acknowledge? :)
George Powell - Wednesday, March 18, 2009 - link
I believe it refers to consumer drives. While SAS drives are beginning to be a possibility on the desktop with newer motherboards supporting them natively, the drives themselves are too expensive and too noisy for most consumers to actually want them.FishTankX - Wednesday, March 18, 2009 - link
Good info. However, I noticed one mistake.Second page
Samsung had a MLC controller at the time but it was too expensive than what SuperTalent was shooting for.