The SSD Relapse: Understanding and Choosing the Best SSD
by Anand Lal Shimpi on August 30, 2009 12:00 AM EST- Posted in
- Storage
Tying it All Together: SSD Performance Degradation
More spare area is better for random workloads, but desktop workloads aren’t random enough to justify setting aside more spare area to improve performance; most reviews don’t test in a used state, and more users would simply flock to lower price-per-GB drives with less spare area.
Drives that drop the most in performance from new to used state have the most to gain from the TRIM instruction. Depending on how you use your drive of course:
| % Performance Drop in Used State vs. New State | |||
| 4KB Random Write | 2MB Sequential Write | PCMark Vantage HDD Suite | |
| Intel X25-E 64GB (SLC) | 26.1% | 5.4% | 9.7% |
| Intel X25-M G1 160GB (MLC) | 35.5% | 3.8% | 16.7% |
| Intel X25-M G2 160GB (MLC) | 0.7% | 2.2% | 15.3% |
| OCZ Agility 128GB (Indilinx MLC) | 44.8% | 15.0% | 4.4% |
| OCZ Summit 256GB (Samsung MLC) | 72.4% | 3.0% | 23.6% |
| OCZ Vertex EX 128GB (Indilinx SLC) | 60.5% | 20.8% | 0.8% |
| OCZ Vertex Turbo 128GB (Indilinx MLC) | 44.0% | 15.4% | 4.5% |
| Patriot Torqx 128GB (Indilinx MLC) | 44.6% | 15.6% | 3.5% |
Depending on the scenario, all three controllers have a lot to gain from TRIM. Random write performance drops significantly for almost every single drive. The worst is the Samsung RBB controller, which lost over 70% of its performance between new and used states; Samsung needs TRIM.
Intel made some significant improvements going from the G1 to G2 drives, the new drive loses no performance in our random write test. This is thanks to firmware tweaks and having twice as much DRAM to track data in; the more data the Intel drive can keep track of, the better it is at organization, management and garbage collection. From a pure performance standpoint, the G2 might actually be better for server workloads than the X25-E. In terms of lifespan however, the X25-E has the G2 beat.
Only the Indilinx drives lose an appreciable amount of performance in the sequential write test, but they are the only drives to not lose any performance in the more real-world PCMark Vantage HDD suite. Although not displayed here, the overall PCMark Vantage score takes an even smaller hit on Indilinx drives. This could mean that in the real world, Indilinx drives stand to gain the least from TRIM support. This is possibly due to Indilinx using a largely static LBA mapping scheme; the only spare area is then the 6.25% outside of user space regardless of how used the drive is.
Both Samsung and Intel have a lot to gain from TRIM. Samsung’s performances goes from utterly unacceptable to reasonable (but not price justified) with TRIM. Intel’s performance goes from class-leading to more, er, class-leading.
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zodiacfml - Wednesday, September 2, 2009 - link
Very informative, answered more than anything in my mind. Hope to see this again in the future with these drive capacities around $100.mgrmgr - Wednesday, September 2, 2009 - link
Any idea if the (mid-Sept release?) OCZ Colossus's internal RAID setup will handle the problem of RAID controllers not being able to pass Windows 7's TRIM command to the SSD array. I'm intent on getting a new Photoshop machine with two SSDs in Raid-0 as soon as Win7 releases, but the word here and elsewhere so far is that RAID will block the TRIM function.kunedog - Wednesday, September 2, 2009 - link
All the Gen2 X-25M 80GB drives are apparently gone from Newegg . . . so they've marked up the Gen1 drives to $360 (from $230):http://www.newegg.com/Product/Product.aspx?Item=N8...">http://www.newegg.com/Product/Product.aspx?Item=N8...
Unbelievable.
gfody - Wednesday, September 2, 2009 - link
What happened to the gen2 160gb on Newegg? For a month the ETA was 9/2 (today) and now it's as if they never had it in the first place. The product page has been removed.It's like Newegg are holding the gen2 drives hostage until we buy out their remaining stock of gen1 drives.
iwodo - Tuesday, September 1, 2009 - link
I think it acts as a good summary. However someone wrote last time about Intel drive handling Random Read / Write extremely poorly during Sequential Read / Write.Has Aanand investigate yet?
I am hoping next Gen Intel SSD coming in Q2 10 will bring some substantial improvement.
statik213 - Tuesday, September 1, 2009 - link
Does the RAID controller propagate TRIM commands to the SSD? Or will having RAID negate TRIM?justaviking - Tuesday, September 1, 2009 - link
Another great article, Anand! Thanks, and keep them coming.If this has already been discussed, I apologize. I'm still exhausted from reading the wonderful article, and have not read all 17 pages of comments.
On PAGE 3, it talks about the trade-off of larger vs. smaller pages.
I wonder if it would be feasible to make a hybrid drive, with a portion of the drive using small pages for faster performance when writing small files, and the majority of it being larger pages to keep the management of the drive reasonable.
Any file could be written anywhere, but the controller would bias small writes to the small pages, and large writes to large files.
Externally it would appear as a single drive, of course, but deep down in the internals, it would essentially be two drives. Each of the two portions would be tuned for maximum performance in different areas, but able to serve as backup or overflow if the other portion became full or ever got written to too many times.
Interesting concept? Or a hair brained idea buy an ignorant amateur?
CList - Tuesday, September 1, 2009 - link
Great article, wonderful to see insightful, in depth analysis.I'd be curious to hear anyone's thoughts on the implications are of running virtual hard disk files on SSD's. I do a lot of work these days on virtual machines, and I'd love to get them feeling more snappy - especially on my laptop which is limited to 4GB of ram.
For example;
What would the constant updates of those vmdk (or "vhd") files do to the disk's lifespan?
If the OS hosting the VM is windows 7, but the virtual machine is WinServer2003 will the TRIM command be used properly?
Cheers,
CList
pcfxer - Tuesday, September 1, 2009 - link
Great article!"It seems that building Pidgin is more CPU than IO bound.."
Obviously, Mr. Anand doesnt' understand how compilers work ;). Compilers will always be CPU and memory bound, reduce your memory in the computer to say 256MB (or lower) and you'll see what I mean. The levels of recursion necessary to follow the production (grammars that define the language) use up memory but would rarely use the drive unless the OS had terrible resource management. :0.
CMGuy - Wednesday, September 2, 2009 - link
While I can't comment on the specifics of software compilers I know that faster disk IO makes a big difference when your performing a full build (compilation and packaging) of software.IDEs these days spend a lot their time reading/writing small files (thats a lot of small, random, disk IO) and a good SSD can make a huge difference to this.