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2014/04/26 Btrfs Tips: Cancel A Btrfs Scrub That Is Already Stopped

π 2014-04-26 01:01 in Btrfs, Linux

How to cancel a btrfs scrub that won't cancel

In some cases, btrfs scrub can be interrupted in a way that leaves it in a half state. State is stored in /var/lib/btrfs/scrub.status.UUID and if the relevant file indicates that scrub is still running (even though it is not), a new scrub cannot be started, nor the already stopped one cancelled.

This is fixed as shown below:

Problem:

gargamel:~# btrfs scrub start -d /dev/mapper/dshelf1
ERROR: scrub is already running.
To cancel use 'btrfs scrub cancel /dev/mapper/dshelf1'.
gargamel:~# btrfs scrub status  /dev/mapper/dshelf1
scrub status for 6358304a-2234-4243-b02d-4944c9af47d7
        scrub started at Tue Apr  8 08:36:18 2014, running for 46347 seconds
        total bytes scrubbed: 5.70TiB with 0 errors
gargamel:~# btrfs scrub cancel  /dev/mapper/dshelf1
ERROR: scrub cancel failed on /dev/mapper/dshelf1: not running

Fix:

gargamel:~# perl -pi -e 's/finished:0/finished:1/' /var/lib/btrfs/*

Verification:

gargamel:~# btrfs scrub status  /dev/mapper/dshelf1
scrub status for 6358304a-2234-4243-b02d-4944c9af47d7
        scrub started at Tue Apr  8 08:36:18 2014 and finished after 46347 seconds
        total bytes scrubbed: 5.70TiB with 0 errors
gargamel:~# btrfs scrub start -d /dev/mapper/dshelf1
scrub started on /dev/mapper/dshelf1, fsid 6358304a-2234-4243-b02d-4944c9af47d7 (pid=24196)

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How to cancel a btrfs scrub that won't cancel