[colug-432] md (linux drive mirroring)

[Jeff Frontz]

Thanks, Russ -- So the "U to -" change doesn't have an associated dmesg?
Or is the "raid5: Disk failure on sdf1, disabling device" what would
accompany it?  I'm assuming a single hard failure is enough to take a
drive/slice out of the array?

What kernel is this on?  My md module apparently outputs "md:"-prefixed
messages and the only thing I've ever seen from it is for the periodic
"data-check of RAID array". There was definitely nothing from it when there
were reports from sd about unrecoverable read errors (and associated
message about EIO from blk_update_request).

Unfortunately, the system is remote and all I have is syslog/journald
output (I can't run mdadm or the like).

Jeff


On Wed, Aug 21, 2019 at 3:16 PM R P Herrold <herrold at owlriver.com> wrote:

>
> When a drive 'falls out' of the array, the 'U' changes to '-'
> or such.  I have a 'cron' process which watches for such, and
> provides notification
>
> ...
>
> from the 'dmesg' on a recent failure:
>
> end_request: I/O error, dev sdf, sector 2563365089
> sd 0:0:5:0: SCSI error: return code = 0x08000002
> sdf: Current: sense key: Medium Error
>     Add. Sense: Unrecovered read error
>
> end_request: I/O error, dev sdf, sector 2563365033
> raid5:md0: read error NOT corrected!! (sector 2563365032 on
> sdf1).
> raid5: Disk failure on sdf1, disabling device. Operation
> continuing on 14 devices
> raid5:md0: read error not correctable (sector 2563365040 on
> sdf1).
> raid5:md0: read error not correctable (sector 2563365048 on
> sdf1).
>
> ( as you can see the device failed, and was 'disabled' and
> dropped out of the array )
>
>
>
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