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I know this question has probably been asked at some point in the past, but I am trying to figure out if Windows 7 supports passing TRIM commands through RAID controllers yet.

I am trying to decide between buying a single SSD drive and utilizing TRIM or Buying two SSD drives and putting them in RAID 0 configuration

What is the fastest current configuration I can set up?

I want my development machine to be BLAZING fast.

KronoS wants an update on this:

I'm looking to see if there's an update on this, as I currently have a RAID 0 setup with two SSD drives. Will a TRIM supported SSD in RAID0 array correctly pass the TRIM command?

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4 Answers

up vote 3 down vote accepted

Some Intel storage controllers will pass TRIM to SSDs, when the controller is in RAID mode, and some hard drives are RAIDed. However, at the moment, the SSDs must not be in RAID in order to receive TRIM.

This will also depend on the specific SSD(s) you plan to buy. AnandTech recently compared the performance of 2 x 40GB Intel X25-V SSDs in RAID-0 to other (non-RAID) SSDs. The sequential write and (aligned) random write speeds are improved, but there are still better single-SSD options available, which will not suffer from the loss of TRIM.

Update: For Windows 7, I cannot find any evidence that SSDs in hardware or software RAID 0 will accept TRIM. Intel Rapid Storage Technology has been updated from version 9.6 to 10.1, but does not add this feature. Nevertheless, this might be possible using software RAID with btrfs (and Linux):

As I understand it, hardware RAID controllers do not pass the TRIM command to it's disks; btrfs deals with the disk directly, supports TRIM, and supports RAID. I have seen no explicit mention of being able to combine RAID and TRIM support using btrfs with independent disks so I'm asking: When btrfs is in RAID mode, does it still pass the TRIM commands to the SSD?

If TRIM is enabled then yes it should.

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Ok, that makes sense. So if given the choice between 1 Crucial RealSSD C300 256GB or 2 Crucial RealSSD C300 128GB in RAID 0. Which is faster? Would the lack of trim be overcome by the RAID 0 speed? – John Sonmez May 12 '10 at 13:35
@John It's hard to say for sure without benchmarks, but I'd guess the RAID-0 option would be fastest, at least initially. Personally I'd prefer one larger SSD because SSDs tend to be faster the more free space that is available (and TRIM will help maintain the pool of free space over time), and because of the slight hassle that RAID adds. The sequential speeds ought to be through the roof with C300s in RAID-0 (especially with 6Gb/s SATA); but often the random read/write speeds dominate in real-life performance. – sblair May 12 '10 at 21:38
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up vote 4 down vote
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TRIM still does not seem to be supported on RAID, whether software or hardware or level 0 or more, and it also seems that Microsoft is not to blame in this case.

From Intel Rapid Storage Technology :

Is there TRIM support for RAID configurations?

Intel® Rapid Storage Technology 9.6 supports TRIM in AHCI mode and in RAID mode for drives that are not part of a RAID volume.

A defect was filed to correct the information in the Help file that states that TRIM is supported on RAID volumes.

For the current Intel Rapid Storage Technology version 10, the article What features are supported on each I/O controller hub (ICH)? still mentions :

TRIM support in Windows 7* (in AHCI and RAID mode for drives not part of a RAID volume)

The article software RAID/LVM TRIM support on Linux confirms this fact for Linux, but offers a workaround that conserves TRIM and has the same effect as RAID-0, but without using RAID.

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So in essence there's no support whatsoever for TRIM on any RAID configuration of SSD's. Sad. – KronoS May 7 '11 at 22:28
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@KronoS: The only supported RAID configurations for TRIM are (1) the trivial case of one disk, or (2) when a disk is used as non-member of a RAID. – harrymc May 9 '11 at 6:36
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up vote 2 down vote

As of right now: No RAID controllers I know of are passing TRIM commands down to connected SSDs.

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up vote 1 down vote

As an aside, you can find out if trim is working by starting cmd and entering;

fsutil behavior query DisableDeleteNotify

A result of 0 indicates it is.

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