Re: software RAID

[Valdis.Kletnieks@vt.edu]

On Fri, 20 May 2005 16:03:34 EDT, Lennart Sorensen said:

> If you have a bad sector, it doesn't go away by writing to it again.  On
> modern drives, if you see bad sectors the disk is just about dead, and
> will probably be seen as such by the raid system which will then stop
> using the disk entirely and expect you to replace it ASAP.

The one exception here is if you have a miswritten sector (usually caused by
unexpected power-down), which won't read back correctly - but running badblocks
with one of the 'write-verify' options will resurrect it.

If you have a drive that has a bad block in it even *after* badblocks has
re-written it, it's time to replace the drive *now*....

For the original poster: Breaking the mirror and then re-mirroring from the
"good" drive *might* recover the bad block when it re-writes it.  But don't bet
on it...

("power fail" is about the only cause of recoverable bad blocks that I know of -
and if you're having power-fail issues on a RAID, I'd recommend you fix
*THAT* problem before it causes you more grief.  A good UPS will more than pay
for itself in sysadmin sanity and peace of mind....)

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