Re: recovering from a disk failure via raid

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Tue, Jun 24, 2008 at 11:08:43AM -0400, Steven M. Bellovin wrote:
> One of two drives I have in a raid1 configuration is showing a read
> error.  The kernel properly detected this and failed the drive.  The
> question, of course, is now what?
> 
> The first choice, of course, is to install a replacement drive.  How do
> I initiate the recopy?  'raidctl -R'?  (Is it worth just doing that
> without replacing the drive, on the grounds that rewriting a bad sector
> will sometimes cause the drive to switch to a spare?)

It's worth it. I've done it several times with success.
The read error could also be caused by transient failure ...


> 
> But perhaps it doesn't pay to replace the drive -- it's pretty full,
> and besides, 60GB drives aren't easy to find these days...  If I were
> to buy two new drives, what is the best way to set up a RAID1 on the
> new pair?  Install one new drive as the sole member of a RAID1 set,
> install everything on it, then replace the old 60GB drive with the
> second and initiate reconstruction?

that would work, but you wouldn't use the extra space on the drive.
Another way is to setup the second drive as a member of another
raid-1 in degraded mode, newfs and copy the data the usual way, remplace
the old drive and initiate a reconstruct. This way you'll use the
extra space of the new drive.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--