Re: recovering from a disk failure via raid

[Wouter Klouwen <dublet%acm.org@localhost>]

Steven M. Bellovin(smb%cs.columbia.edu@localhost) said 2008.06.24 11:08:43 
+0000:
> The first choice, of course, is to install a replacement drive.  How do
> I initiate the recopy?  'raidctl -R'?  

That's what the manpage says. While the reconstruction is going on, run
raidctl -S to tell you when it should be complete.

> (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?)

Given that you've got the drives in RAID1, you value data integrity. If one
of the drives is starting to show bad sectors, surely it pays to replace it.

> 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 seems the safest way of migrating the data, and certainly the way I
would do it. 

> 
>               --Steve Bellovin, http://www.cs.columbia.edu/~smb