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As of the current (3.10+) Linux kernels, is it supported to make a btrfs RAID 0 out of SSDs the root mount and boot to it? This comprises several issues:

  • Does the RAID 0 with SSDs support TRIM/discard blocks? (According to docs, definitely supported for a single drive but unclear for RAID)
  • Does btrfs block alignment work properly in a RAID 0?
  • Will grub/grub2 be able to boot to a btrfs RAID 0? (Seems like grub2 only but would like confirmation)
  • More generally, how stable and well-supported is this configuration right now? Does anyone use it?


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When you say RAID, are you meaning the RAID capabilities of BTRFS, or softRAID (mdadm)? – dawud Sep 19 '13 at 6:41
@dawud of course the btrfs RAID. Having a RAID-aware fs definitely allows more features than a RAID-agostic one. Additionally I'm pretty sure mdadm doesn't support TRIM over RAID 0. – Andrew Mao Sep 19 '13 at 6:43

Discard works fine, block alignment is nothing special, and btrfs multi-device support (profiles: raid0 raid1 raid10 dup) has been there since the beginning. Be prepared to use a recent kernel nonetheless because the Btrfs developers don't do a lot of stable backports.

You should use a separate /boot; Grub supports most Btrfs features (including compression and the above raid levels), but Btrfs recently added skinny extents which you will want to enable.

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I'm specifically asking about all of the above at the same time, instead of just separately. Can one get discard properly when using RAID 0? – Andrew Mao Sep 20 '13 at 14:32

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