The SSD Relapse: Understanding and Choosing the Best SSD
by Anand Lal Shimpi on August 30, 2009 12:00 AM EST- Posted in
- Storage
Used vs. New Performance: Revisited
Nearly all good SSDs perform le sweet when brand new. None of the blocks have any data in them, each write is performed at full speed, all is bueno. Over time, your drive gets written to, all blocks get occupied with data (both valid and invalid) and now every time you write to the SSD its controller has to do that painful read modify write and cleaning.
In the Anthology I simulated this worst used case by first filling the drive with data, deleting the partition, then installing the OS and running my benchmarks. This worked very well because it filled every single flash block with data. The OS installation and actual testing added a few sprinkles of randomness that helped make the scenario even more strenuous, which I liked.
The problem here is that if a drive properly supports TRIM, the act of formatting the drive will erase all of the wonderful used data I purposefully filled the drive with. My “used” case on a drive supporting TRIM will now just be like testing a drive in a brand new state.
To prove this point I provide you with an example of what happens when you take a drive supporting TRIM, fill it with data and then format the drive:
| SuperTalent UltraDrive GX 1711 | 4KB Random Write IOPS |
| Clean Drive | 13.1 MB/s |
| Used Drive | 6.93 MB/s |
| Used Drive After TRIM | 12.9 MB/s |
Oh look, performance doesn’t really change. The cleaning process takes longer now but other than that, the performance is the same.
So, I need a new way to test. It’s a shame because I’m particularly attached to the old way I tested, mostly because it provides a very stressful situation for the drives to deal with. After all, I don’t want to fool anyone into thinking a drive is faster than it is.
Once TRIM is enabled on all drives, the way I will test is by filling a drive after it’s been graced with an OS. I will fill it with both valid and invalid data, delete the invalid data and measure performance. This will measure how well the drive performs closer to capacity as well as how well it can TRIM data.
Unfortunately, no drives properly support TRIM yet. The beta Indilinx firmware with TRIM support works well, unless you put your system to sleep. Then there’s a chance you might lose your data. Woops. There’s also the problem with Intel’s Matrix Storage Manager not passing TRIM to your drives. All of this will get fixed before the end of the year, but it’s just a bit too early to get TRIM happy.
What we get today is the first stage of migrating the way we test. In order to simulate a real user environment I take a freshly secure erased drive, install Windows 7 x64 on it (no cloning, full install this time), then install drivers/apps, then fill the remaining space on the drive and delete it. This fills the drive with invalid data that the drive must keep track of and juggle, much like what you'd see by simply using your system.
I’m using the latest IMSM driver so TRIM doesn’t get passed to the drives; I’m such a jerk to these poor SSDs.
I’ll start look at both new and used performance on the coming pages. Once TRIM gets here in full force I’ll just start using it and we won't have to worry about looking at new vs. used performance.
The Test
| CPU | Intel Core i7 965 running at 3.2GHz (Turbo & EIST Disabled) |
| Motherboard: | Intel DX58SO (Intel X58) |
| Chipset: | Intel X58 |
| Chipset Drivers: | Intel 9.1.1.1015 + Intel IMSM 8.9 |
| Memory: | Qimonda DDR3-1066 4 x 1GB (7-7-7-20) |
| Video Card: | eVGA GeForce GTX 285 |
| Video Drivers: | NVIDIA ForceWare 190.38 64-bit |
| Desktop Resolution: | 1920 x 1200 |
| OS: | Windows 7 x64 |
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nemitech - Monday, August 31, 2009 - link
opps - not ebay - it was NEWEGG.Loki726 - Monday, August 31, 2009 - link
Thanks a ton for including the pidgin compiler benchmarks. I didn't think that HD performance would make much of a difference (linking large builds might be a different story), but it is great to have numbers to back up that intuition. Keep it up.torsteinowich - Monday, August 31, 2009 - link
HiYou write that the Indilinx wiper tool collects a free page list from the OS, then wipes the pages. This sounds like a dangerous operation to me since the OS might allocate some of these blocks after the tool collects the list, but before they are wiped.
Have you received a good explanation for Indilinx about how they ensure file system integrity? As far as i know Windows cannot temporarily switch to read-only mode on an active file system (at least not the system drive). The only way i could see this tool working safely would be by booting off a different media and accessing the file system to be trimmed offline with a tool that correctly identifies the unused pages for the particular file system being used. I could be wrong of course, maybe windows 7 has a system call to temporarily freeze FS writes, but i doubt it.
has407 - Monday, August 31, 2009 - link
It: (1) creates a large temporary file (wiper.dat) which gobbles up all (or most) of the free space; (2) determines the LBA's occupied by that file; (3) tells the SSD to TRIM those LBA's; and then (4) deletes the temporary file (wiper.date).From the OS/filesystem perspective, it's just another app and another file. (A similar technique is used by, e.g., sysinternals Windows SDelete app to zero free space. For Windows you could also probably use the hooks used by defrag utilities to accomplis it, but that would be a lot more work.)
cghebert - Monday, August 31, 2009 - link
Anand,Great article. Once again you have outclassed pretty much every other site out there with the depth of content in this review. You should start marketing t-shirts that say "Everything I learned about SSDs I learned from AnandTech"
I did have a question about gaming benchmarks, since you made this statement:
" but as you'll see later on in my gaming tests the benefits of an SSD really vary depending on the game"
But I never saw any gaming benchmarks. Did I miss something?
nafhan - Monday, August 31, 2009 - link
Just wanted to say awesome review.I've been reading Anandtech since 2000, and while other sites have gone downhill or (apparently) succumbed to pressure from advertisers, you guys have continued to give in depth, critical reviews.
I also appreciate that you do some real analysis instead of just throwing 10 pages of charts online.
Thanks, and keep up the good work!
zysurge - Monday, August 31, 2009 - link
Awesome amazing article. So much information, presented clearly.Question, though? I have an Intel G2 160GB drive coming in the next few days for my Dell D830 laptop, which will be running Windows 7 x64.
Do I set the controller to ATA and use the Intel Matrix driver, or set it to AHCI and use Microsoft's driver? Will either provide an advantage? I realize neither will provide TRIM until Q4, but after the firmware update, both should, right?
Thanks in advance!
ggathagan - Wednesday, September 16, 2009 - link
From page 15 (Early Trim support...):Under Windows 7 that means you have to use a Microsoft made IDE or AHCI driver (you can't install chipset drivers from anyone else).
Mumrik - Monday, August 31, 2009 - link
but I can't live with less than 300GB on that drive, and SSDs in usable sizes still cost more than high end video cards :-(I really hope I'll be able to pick up a 300GB drive for 100-200 bucks in a year or so, but it is probably a bit too optimistic.
Simen1 - Monday, August 31, 2009 - link
This is simply wrong. Ask anyone over 10 years if they think this mathematical statement is true or false. 80 can never equal 74,5.Now, someone claims that 1 GB = 10^9 B and others claim that 1 GB is 2^30 B. Who is really right? What does the G and the B mean? Who defines that?
The answers is easy to find and document. B means Byte. G stands for Giga ans means 10^6, not 2^30. Giga is defined in the international system of units, SI.
No standardization organization have _ever_ defined Giga to be 2^30. But IEC, International Electrotechnical Commission, have defined "Gi" to 2^30. This is supposed to be used for digital storage so people wont be confused by all the misunderstandings around this. Misunderstandings that mainly comes from Microsoft and quite a few other big software vendors. Companies that ignore the mathematical errors in their software when they claim that 80GB = 74,5 GB, and ignore both international standards on how to shorten large numbers.