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Re: Scheduling btrfs scrub on desktop systems

On Tue, Apr 02, 2013 at 12:12:10PM +0100, Jonathan Dowland wrote:
> On Mon, Apr 01, 2013 at 05:25:48PM +0200, Steven Post wrote:
> > But what if the system is powered down during a scrub? Will it continue
> > when it boots up again?
> > All assuming the scrub is started with 'btrfs scrub start -B <path>'.
> Why not start a scrub on reboot via @reboot in cron, too. Or would you
> prefer it if you didn't always scrub upon boot?

On my newly built system, a btrfs scrub across two disks (data
and metadata both RAID1) runs at about 10GB per minute. That's
GB of data/metadata in-use, not disk capacity. Still, when you
have a 2TB filesystem that's mostly full, a scrub will take more
than three hours.

You can't stop people shutting down their systems, but you can
pause a scrub.

btrfs scrub cancel DEVICE

in the shutdown script, and

btrfs scrub resume DEVICE

in the startup script will pick it up from where it left off.

Or, you could solve this with a social cue: "please don't turn
off desktops on weekends. We run maintenance then."


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