Intel releases SSD friendly AHCI/RAID driver
Subject: Storage | March 24, 2010 - 06:00 PM | Allyn Malventano
For the past few months, Intel has been working on a new Rapid Storage Technology (RST) driver to replace the old Intel Matrix Storage Manager (IMSM) series.
- In AHCI mode, passes TRIM to attached SSD's.
- In RAID mode, passes TRIM to attached single SSD's.
This tidbit is likely, but unconfirmed at present:
- In RAID mode, passes TRIM to SSD's in RAID 0, 1, and 0+1 (RAID-5 is not supported).
RAID-5 won't properly support TRIM because if you were to TRIM a part of a stripe across the array, parity would fail on a subsequent rebuild.
The unconfirmed bit has been confirmed as unconfirmed from Intel:
“Intel® RST 9.6 supports TRIM in AHCI and pass through modes for RAID. A bug has been submitted to change the string that indicates TRIM is supported on RAID volumes (0,1,5,10). Intel is continuing to investigate the ability of providing TRIM support for all RAID volumes in a future release”
Looks like we'll have to wait a little longer for TRIM through RAID, but there *are* other SSD-specific improvements in this new driver.
*** END UPDATE ***
A few have already tooled around with the driver, and seen some nice gains in performance by simply doing an in-place upgrade of their current driver. A few notes from my own testing thus far (and throughout their beta):
- This driver is more CPU hungry at higher queue depths due to the advanced caching that takes place to better stripe across SSD's (especially noticeable during random writes).
- The current (1.2) version of SSD Toolbox can not manually optimize / TRIM SSD's in a RAID.
For those already running Windows 7 behind a set of RAIDed SSD's, this driver should TRIM your drives through normal use and will eventually bring them to where they should be (without the need to manually TRIM). If you're under XP or Vista, don't feel left out. This driver won't magically add TRIM support for your OS, but it will increase random write performance of RAIDed SSD's.