Re: Help understanding the root cause of a member dropping out of a RAID 1 set.

On Thu Aug 13, 2009 at 05:26:39PM +0100, John Robinson wrote:

On Thu, 13 August, 2009 5:13 pm, Billy Crook wrote:

quoted

On Thu, Aug 13, 2009 at 03:44, Simon Jackson[off-list ref] wrote:

[...]

quoted

quoted

2009-08-11T06:21:08-07:00 Metro-1 kernel: [556573.348168] md:
super_written gets error=-5, uptodate=0

mdraid notices.  says oh craps.

quoted

2009-08-11T06:21:08-07:00 Metro-1 kernel: [556573.348168] raid1:
Operation continuing on 1 devices.

mdraid marks the component that encountered the error failed, and
keeps on keeping on

quoted

2009-08-11T06:21:08-07:00 Metro-1 kernel: [556573.348168] ata1: EH
complete

ata reset (of link, and subsequently drive) is complete.

Can or could md be made or configured to try re-adding a device if this
sort of thing happens? After all, a stray cosmic ray or whatever perhaps
shouldn't make one lose redundancy if the drive's actually OK?

If you want to do this, it should be doable via the PROGRAM option in
mdadm.conf (using standard mdadm calls).  As has been pointed out
elsewhere though, doing so automatically can be rather a risky option.

Cheers,
    Robin
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