Re: shall distros run btrfsck on boot?

[Jeff Mahoney <jeffm@suse.com>]

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On 11/23/15 11:02 PM, Christoph Anton Mitterer wrote:
> Hey.
> 
> Short question since that came up on debian-devel.
> 
> Now that btrfs check get's more and more useful, are the
> developers going to recommend running it periodically on boot (of
> course that wouldn't work right now, as it would *always* check)?

Running fsck on boot is a holdover from an era where non-journaling
file systems were the norm.  It persists in the ext* world mostly due
to inertia, but it shouldn't be run on boot with ext3 or ext4 either.
 As Eric noted, fsck.xfs is a no-op.  We have something similar for
btrfs and have no intention of ever running fsck on boot with btrfs
except in the case of a mount failure of the root file system.

> Plus... is btrfs check (without any arguments) non-desctructive, or
> are there corner-cases where it may lead to any changes on the
> devices?

I haven't reviewed it in detail, but a quick glance makes it look like
it will, minimally, create transactions even in check-only mode.

- -Jeff

- -- 
Jeff Mahoney
SUSE Labs
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