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Forum Discussion
RAID re-sync with BTRFS scrub
I've not had a ReadyNAS with a multi-tier XRAID volume for so long, I'm not sure of this. Am I correct that the standard UI-initiated or scheduled scrub will do a RAID re-sync on all RAID groups of ...
Thanks. Looking at the log, I now see it did do both sync's. The difference from what I (at least thought I) remembered is that it doesn't have one going and one pending at the beginning. It (now?) requests the second sync after the first completes.
And having looked at it, I see it's struggling with one drive, though all that drive's SMART shows is one pending sector. All the errors but one were correctable, so I guess that's associated with the pending sector, but you'd think the OS would alert you to something being amiss when there are a dozen errors like this:
[Wed May 11 14:50:56 2022] md/raid:md127: read error corrected (8 sectors at 2704135552 on sdf3).
The drive in question being one of the older, smaller ones, I'm going to replace it with a bigger one. But this removed drive won't get relegated to a backup unit, as I have done with the ones replaced just to increase storage.
But the fact that they were corrected should serve notice to those not running periodic scrubs. If not for the scrub, these would not have been corrected, and likely would continue to accumulate.
Sandshark wrote:
Thanks. Looking at the log, I now see it did do both sync's. The difference from what I (at least thought I) remembered is that it doesn't have one going and one pending at the beginning. It (now?) requests the second sync after the first completes.
FWIW, I looked at mdstat partway through the scrub, and saw this:
Personalities : [raid0] [raid1] [raid10] [raid6] [raid5] [raid4]
md126 : active raid5 sda4[0] sdd4[3] sdc4[2] sdb4[1]
11717352576 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
resync=DELAYED
md127 : active raid5 sda3[5] sdd3[7] sdc3[6] sdb3[4]
17567012352 blocks super 1.2 level 5, 64k chunk, algorithm 2 [4/4] [UUUU]
[=========>...........] resync = 45.1% (2643152640/5855670784) finish=1293.6min speed=41386K/sec
So I think the ReadyNAS application is requesting both at the beginning, but mdadm is delaying the second one until the first one completes.
Sandshark wrote:
And having looked at it, I see it's struggling with one drive, though all that drive's SMART shows is one pending sector. All the errors but one were correctable, so I guess that's associated with the pending sector, but you'd think the OS would alert you to something being amiss when there are a dozen errors like this:
[Wed May 11 14:50:56 2022] md/raid:md127: read error corrected (8 sectors at 2704135552 on sdf3).
I agree that the OS should give more alerts on disk issues than it does. IMO, all disk errors should be shown in the UI log (along with increases in the SMART error counts).
OK, that's what I was expecting. But maybe it's different because it's FlexRAID instead of XRAID, because it's a 12-bay rack-mount unit, or because of the way I created the second RAID group manually. Doesn't really matter since it did do the re-sync on both. Thanks for letting me know what's "normal".
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