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.
just to add to the chorus of praise: this is a superbly informative article, thank you for all the effort, and I hope that it has paid off for you, as I'm sure it must have.
My first question is this. Is it possible to analyse a program while you're using it, to see whether it is primarily doing sequential or random writes? Since there seems to be a quite clear difference between the Intel X25m 80gb and the OCZ vertex 120gb, which are the natural entry-level drives here, where the Intel works better for random access, the vertex for sequential, it would be very useful to know which I would make best use of.
Second question: does anyone know whether lightroom in particular is based around random or sequential writes? I know that a LR catalog is always radically fragmented, which suggests presumably that it is based around random writes, but that's just an uninformed guess. It does have a cache function, which produces files in the region of 3-5mb in size--are they likely to be sequential?
Third question: with photoshop, is it specifically as a scratch disk that the intel x25m underperforms? Or does photoshop do other sequential writes, besides those to the scratch disk? I ask because if it only doesn't work as a scratch disk, then that's not a big problem--anyone using this in a PC is likely to have a decent regular HDD for data anyway, so the scratch disk can just be sent there. In fact, I've been using a vertex 120gb, with a samsung spinpoint f3 500gb on my PC, and I found that with the scratch disk on the samsung I got better retouch artists results (only by about half a second, but that's out of 14 seconds, so still fairly significant).
Thanks in advance to anyone who might be able to answer, and thanks again Anand for such an informative read.
Cheers
Seth