The SSD Relapse: Understanding and Choosing the Best SSDby Anand Lal Shimpi on August 30, 2009 12:00 AM EST
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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.