Windows 7 / TRIM testingTRIM refresher
TRIM is an additional command recently added to the ATA specification. It allows the Operating System to tell a storage device (in this case the SSD) which sector ranges are no longer needed for storage. In the absence of such a command, the SSD has to assume all sectors contain useful data. This results in a drop in IOPS performance as sectors are used, as well as a potential drop in sequential write performance in the cases where random writes have resulted in excessive LBA remap table fragmentation. TRIM helps avoid these downfalls.
To ensure Windows 7 was correctly implementing TRIM, I tested on a few different sets of hardware. The test was simple:
- Fragment an SSD using one of my Torture Testing Tools ™
- Format the first ~60GB using the Windows 7 install environment
- Install Windows 7
- From within Windows 7, create and format another small partition after the primary
(leaving at least some of the SSD area leftover and unused)
- Shutdown and place the SSD back on the testbed and evaluate performance
Indilinx with TRIM enabled firmware (1819):
Both of the above showed TRIM working as expected. The OS and additional partition took the first section of the drive. Write speed falls off for untrimmed areas. Intel and Indilinx both handle things differently but the net result is similar (and favorable).
In my testing I noted an issue with the above scenario when done under an Intel ICH8M equipped laptop:
The TRIMmed area should have extended much further, but some oddissue caused only the first 16GB of each partition to see the effects of TRIM. ICH8 was designed before ATA TRIM was developed, so it may be some sort of hardware limitation or perhaps something Intel will tweak with later drivers.
Intel’s SSD Toolbox warrants a quick mention here. The application is quite simple and lets you observe SMART data from an X25-M or E SSD (G1 or G2). G2 users with the new firmware will get some additional options, the most important of which is the ability to TRIM your X25-M G2 on demand, even under non-TRIM enables operating systems like XP and Vista.
The tool gets the job done nicely and you can even schedule it to run daily for complete hands off operation. The optimization run takes only 3-5 seconds regardless of level of the level of fragmentation present. Windows 7 users should not need scheduled runs so long as they are operating in AHCI mode.