[OpenAFS] Volume backup in distinct server

[Derek Atkins]

Hi,

The backup volume is meant for user access to backup data, not for
"replication across servers".  It's on the same server to reduce
the amount of disk space that is used.  It's purpose is not to protect
against lost disks, it's purpose is to protect against "rm".

What you seem to want is ReadWrite replication, which is something
that AFS does not do.

One thing you CAN do is make a RO clone on the same server/partition
as the RW (as well as on the other server).  The local RO clone wont
take up much disk space (it's a clone after all, just like the Backup
volume), but it does help in terms of the locking.  The RW only gets
locked in order to make the clone, and then the clone is copied across
the net.  This means your RW volume isn't locked for the whole release
process, only during the clone.

-derek

Joao Pedro Barreto <jpbarreto@gsd.inesc-id.id> writes:

> Hi,
> 
> I administer an AFS domain which has two servers storing file volumes.
> I wanted to configure volume backup, so that each volume stored in one
> server's disk would be replicated (or backed up) in the other server's
> disk.
> My first approach was to create read-only replicas of each volume. For
> instance, if a volume was stored in server A, I would create a
> read-only volume for it on server B. However, I soon discovered that
> the release of volumes (which I'd perform daily in order to update the
> read-only volumes) NEEDS TO LOCK the original volume, which can be a
> serious drawback if we consider that most volumes are sufficiently big
> to take some hours to be released.
> I then found about the backup functionality which, according to AFS
> documentation, should be the best choice for my problem. Mainly, this
> solution doesn't require locking of the original volumes to update the
> backup volumes. However, this option only allows creation of backup
> volumes in the SAME PARTITION (AND SERVER) as the original
> volume. Which, of course, is insuficient to my requirements of having
> backup volumes in distinct computers from their original volumes (so
> that, if a computer fails and its data are lost, the volume can still
> be obtainable from the other computer).
> 
> Does anyone can help me on this? how should I solve my problem?
> 
> Thank you in advance.
> 
> Joao
> jpbarreto _AT_ gsd _DOT_ inesc-id _DOT_ id
> 
> 
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-- 
       Derek Atkins, SB '93 MIT EE, SM '95 MIT Media Laboratory
       Member, MIT Student Information Processing Board  (SIPB)
       URL: http://web.mit.edu/warlord/    PP-ASEL-IA     N1NWH
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