[BBLISA] Notes on RAID recovery Re: Whatever happened to Seagate?

[Dan Ritter]

On Wed, May 06, 2015 at 01:27:05PM -0700, Rich Braun wrote:
> * Once a week, you should force the system to read (or "scrub" or whatever the
> technical term for this is) every block of every drive. The "echo check"
> command above should be performed as part of a script under cron.  That way
> the drives' firmware will detect bit-rot at the earliest opportunity, and
> you'll face less risk of multiple-drive failures.

Debian automatically installs cron jobs for this when you
install the mdadm package. I've attached the script.

> * Whenever you're swapping out a drive, *don't* use the "mdadm --fail" command
> when you want to force resilvering to a replacement drive, especially if a
> software-RAID volume is already in sync. Use "want_replacement" to resilver to
> the new drive (after you've mdadm --add'ed it); that way bitrot on an as
> yet-undetected bad sector won't render your array unreadable.  (Newer versions
> of mdadm have a --replace function to do this for you.)

That's a new one on me! Thanks!

> I also haven't started using ZFS. A lot of people are adopting it to
> automatically take care of most of these issues.

ZFS and btrfs are both remarkably close to being wonderful, but they are
sufficiently different from standard filesystems that you really need
to study up on them and create some playgrounds before you try using
them for data you care about.

-dsr-
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