Jarod Wilson wrote:
The place I want it is as a 3rd member of a RAID1 set that is used for
the pooled file storage for backuppc - which hardlinks all identical
files it finds across your backup set. This is extremely busy during
backups and takes an impractically long time to copy with tar or other
file-oriented means because of the way hardlinks are re-constructed
(many days for a 250 gig drive), while a raid-sync will complete in a
couple of hours. There's probably a better way to do that now with LVM
snapshots but that's getting off the topic of reliability.
Wait... So you're essentially creating a cloned volume on the firewire
disk via a raid resync, rather than having the initial backup written
with the firewire disk connected in the raid set? If so, that's
moderately amusing... :)
The object is to make copies that can be rotated offsite weekly and
that's the first way I found that actually worked. In earlier attempts
I tried to use one internal, one external drive as a mirrored set, just
failing/removing the external drive and adding a different one
periodically. That didn't work well because the drive would frequently
be marked as failed even though it really didn't have a problem, and on
any reboot it would have to be re-synced manually. Also while trying to
do it this way I had an actual failure on the internal drive which took
some contortions to recover. So, I created a 3-member raid1 with one
device specified as "missing" and now have 2 internal drives that run
mirrored all the time and at weekly intervals add the external drive and
wait for the sync. Then I momentarily stop the backuppc service,
unmount the drive, fail the device in the raid, and remove it. I can
then access the external drive with a laptop and could do disaster
recovery restores without any other special equipment. Backuppc's
compression/pooling scheme crams about 700gigs worth of archives on the
250 gig disks that I am using and it beats trying to find things on
tapes. But, for some reason the drive works fine for the 2+ hour sync
procedure but will generally fail out of the raid if I forget and leave
it connected through the nightly backups. My guess is that it isn't
doing as many retries on soft errors or timeouts as a raid member as a
standalone device would.
--
Les Mikesell
lesmikesell@xxxxxxxxx
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