On 1/9/20 11:52 AM, Graham Cobb wrote:
On 09/01/2020 10:34, Holger Hoffstätte wrote:
On 1/9/20 11:03 AM, Sebastian Döring wrote:
Maybe I'm doing it entirely wrong, but I can't seem to get 'btrfs
scrub resume' to work properly. During a running scrub the resume
information (like data_bytes_scrubbed:1081454592) gets written to a
file in /var/lib/btrfs, but as soon as the scrub is cancelled all
relevant fields are zeroed. 'btrfs scrub resume' then seems to
re-start from the very beginning.
This is on linux-5.5-rc5 and btrfs-progs 5.4, but I've been seeing
this for a while now.
Is this intended/expected behavior? Am I using the btrfs-progs wrong?
How can I interrupt and resume a scrub?
Using 5.4.9+ (all of btrfs-5.5) and btrfs-progs 5.4 I just tried and
it still works for me (and always has):
$btrfs scrub start /mnt/backup
scrub started on /mnt/backup, fsid d163af2f-6e03-4972-bfd6-30c68b6ed312
(pid=25633)
$btrfs scrub cancel /mnt/backup
scrub cancelled
$btrfs scrub resume /mnt/backup
scrub resumed on /mnt/backup, fsid d163af2f-6e03-4972-bfd6-30c68b6ed312
(pid=25704)
..and it keeps munching away as expected.
Can you check that the resume has really started from where the scrub
was cancelled? What I (and, I think, Sebastian) are seeing is that the
resume "works" but actually restarts from the beginning.
For example, something like:
btrfs scrub start /mnt/backup
sleep 300
btrfs scrub status -R /mnt/backup
btrfs scrub cancel /mnt/backup
btrfs scrub resume /mnt/backup
sleep 100
btrfs scrub status -R /mnt/backup
and check the last_physical in the second status is higher than the one
in the first status.
Well, yes. Reduced the wait times a bit and:
$cat test-scrub
#!/bin/sh
btrfs scrub start /mnt/backup
sleep 30
btrfs scrub status -R /mnt/backup
btrfs scrub cancel /mnt/backup
btrfs scrub resume /mnt/backup
sleep 10
btrfs scrub status -R /mnt/backup
$./test-scrub
scrub started on /mnt/backup, fsid d163af2f-6e03-4972-bfd6-30c68b6ed312 (pid=26390)
UUID: d163af2f-6e03-4972-bfd6-30c68b6ed312
Scrub started: Thu Jan 9 12:02:18 2020
Status: running
Duration: 0:00:25
data_extents_scrubbed: 65419
tree_extents_scrubbed: 28
data_bytes_scrubbed: 4117274624
tree_bytes_scrubbed: 458752
read_errors: 0
csum_errors: 0
verify_errors: 0
no_csum: 0
csum_discards: 0
super_errors: 0
malloc_errors: 0
uncorrectable_errors: 0
unverified_errors: 0
corrected_errors: 0
last_physical: 3591372800
^^^^^^^^^^^^^^^^^^^^^^^^^
scrub cancelled
scrub resumed on /mnt/backup, fsid d163af2f-6e03-4972-bfd6-30c68b6ed312 (pid=26399)
UUID: d163af2f-6e03-4972-bfd6-30c68b6ed312
Scrub resumed: Thu Jan 9 12:02:49 2020
Status: running
Duration: 0:00:36
data_extents_scrubbed: 12648
tree_extents_scrubbed: 28
data_bytes_scrubbed: 823394304
tree_bytes_scrubbed: 458752
read_errors: 0
csum_errors: 0
verify_errors: 0
no_csum: 0
csum_discards: 0
super_errors: 0
malloc_errors: 0
uncorrectable_errors: 0
unverified_errors: 0
corrected_errors: 0
last_physical: 923205632
^^^^^^^^^^^^^^^^^^^^^^^^
Not sure what I'm doing wrong ;)
-h
