TRIM and RAID

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caboosemoose

Gawd
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What's the current status quo regards the TRIM command for SSDs and running RAID arrays? Last I read Intel had released a storage driver for its chipsets that supported it. I haven't seen anything since. Is the Intel driver / chipset the only one that does it?
 
There is no TRIM on RAID arrays on Windows as of yet.

TRIM on RAID only works on recent Linux kernels with Ext4 and FreeBSD 8.1 with GEOM modules; UFS still requires patches to utilize TRIM.

Likely the first manufacturer who will bring TRIM-on-RAID on Windows-platform will be Intel; i dont think AMD/nVidia/ALi/VIA chipset makes will release drivers that support TRIM on RAID. Their RAID drivers also suck.

Without TRIM, you would best buy the Sandforce SSDs as they appear to be the least affected by loss of TRIM. Due to the compression, they create alot more spare space which helps keeping their performance up. Intel on the other hand appears to degrade rapidly without TRIM.
 
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The TRIM command specification is being standardized as part of the AT Attachment (ATA) interface standard, led by Technical Committee T13 of the International Committee for Information Technology Standards. A TRIM command allows an operating system to tell a solid-state drive (or "SSD") which data blocks are no longer in use, such as those left by deleted files. You should use the OS build-in ATA command device driver to communicate the ATA port for TRIM command. But, most of the RAID adapters emulate the SCSI command to support more volumes on one RAID adapter. That's why the TRIM command can not support on all vendors of RAID adapters. NetAPP just proposal the Trim command for SCSI spec to T10/10-084r0 and 079r0 on 2 March 2010. It may be included the Trim function on the OS in the future. This is the only method to add the function on the firmware level.
Click to expand...

thej biggest problem with trim implementation into raid cards, etc, is inclusion into the SCSI spec. it is the scuzzy spec that is holding us back, not the technology.
 
caboosemoose said:
What's the current status quo regards the TRIM command for SSDs and running RAID arrays? Last I read Intel had released a storage driver for its chipsets that supported it. I haven't seen anything since. Is the Intel driver / chipset the only one that does it?
Click to expand...

there is trim on raid on intel chipsets. the ssd cannot be part of the raid volume. example, two 500gb hdds running in raid 0, and a 60gb ssd as a stand alone drive.
 
sub.mesa said:
There is no TRIM on Windows as of yet.

TRIM on RAID only works on recent Linux kernels with Ext4 and FreeBSD 8.1 with GEOM modules; UFS still requires patches to utilize TRIM.
Click to expand...


OK, this is like the third time I've seen you mention this, do you have any linkage you can share that backs this up?

I've googled quite a bit for TRIM pass-through support in RAID arrays on both linux (ext4) and FreeBSD and about the only real hits I get is either the vague possibility of TRIM on RAID1 arrays (which is pretty trivial since it's just duplication), or posts by you yourself saying that it's possible.

In fact even TRIM on RAID1 seems not to be automatic and requires a shell script to be run (basically a 'manual' TRIM), and even that seems to be iffy.

I'm seriously not trying to come off like an ass, but every time you say this I spend like 30 minutes looking for info because it drives me nuts, lol.
 
BusyBeaverHP: sorry my post was misleading; i meant to say that Windows does not support TRIM on RAID arrays at all. Linux and FreeBSD has limited support for TRIM on RAID; so this is something Microsoft/Intel could be giving you tomorrow; there is no real excuse for the long wait; at least as far as i am aware.

By the way, this support is 100% software; it requires just a TRIM-enabled driver, not some newer piece of hardware.

@Blue Falcon:
The wikipedia has some basic information, though not really accurate. It appears Linux allows you to actually use TRIM on a filesystem (ext4); in FreeBSD the stable releases only support TRIM (BIO_DELETE) on GEOM providers; but there is no filesystem that will issue them, like UFS. There are patches for UFS to send BIO_DELETE on file deletions, they are available for 8-stable and are integrated in 9-CURRENT.

But UFS TRIM support is not what 99% people want; the SSDs likely will not be used for UFS filesystem but for ZFS filesystem instead. ZFS does not support TRIM and may never do; as it makes little sense and copy-on-write filesystems, due to their inherent nature of not overwriting existing data, are much less dependent on TRIM to prevent performance degradation.

So on FreeBSD you can perform a 'secure erase' by TRIMing all LBA on your SSD, or your RAID0 of SSDs, or your mirror of SSDs, etc. The fact that there are RAID modules in between does not matter; each module sends the BIO_DELETE to a lower module.

I think i explained this in more detail somewhere on this board. But too lazy to search. ;-)
 
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