[OpenAFS] Partial replication

[Charles Clancy]

> Do I really have to replicate the volumes?
>
> I know I _WOULD_ like that, but papadoc have roughly 200Gb of disk, and buying
> twice that to be on the replacement is not an option! I just don't have that
> kind of money! I'm doing this (all alone, as a 'private citizen' :) because
> it's fun, not for profit :) Getting a tape (drive) was enough strain on my
> (already bad :) economy...

So, if you're not going to replicate any volumes or the vldb, and your
accounts are already on kerberos, the only thing left is ptserver.  It
seems to me that there's not much point in providing that as a backup
service, if there's no accessable files for the protection server to
protect.

AFS is a File System.  Without any files, there's not much point,
especially if authentication to possibly other services is handled by
kerberos on a seperate machine.

> I got the rough understanding of what the root.* volumes do in a previous mail
> (other topic), and from what I understand, it's not that big a loss if I loose
> these... They can 'easily' (?) be recreated. As long as I have the database
> intact (users etc?), I'm "good to go"... ?

Yeah, I suppose.  You can just as easily back them up too.

> Do I _have to_ (run the file/volume servers) on these machines?

Not if you don't want to.  But as I mentioned before, I wouldn't bother
with having a backup server then.

> The 'only' point (for the time being) in having these replacements was so
> that EVERYTHING is kept intact, and can 'easily' (?) be 're-replicated'
> to the main server if/when it crashes... Sure, the service will be out
> while the repair of papadoc is in progress, but...

Perhaps an easier way would be to just tar up /usr/afs on papadoc, and
keep it in a safe place.  Then if your server crashes, you can just
restore that directory tree, then restore the volumes from tape.

> This is basically only 'live-backups' instead of 'tape/file-backups'.
> Would theoretically mean faster 'up-and-running-after-crash' times...

Well, it depends.  If you don't have enough drive space to replicate all
your volumes and in theory prevent any down-time at all, you want to
replicate enough of them to keep your cell up and running while you repair
the main server.  If the backup servers aren't replicating any volumes,
then there's nothing to keep up-and-running.

[  t charles clancy  ]-[  tclancy@uiuc.edu  ]-[  uiuc.edu/~tclancy  ]