[OpenAFS] Understanding questions backup volume

Lars Schimmer l.schimmer@cgv.tugraz.at
Fri, 10 Feb 2006 15:03:51 +0100

Hash: SHA1

Jeffrey Hutzelman wrote:
> There seems to have been some confusion in this thread, so I guess I
> will speak up...

First: thank you for your long answer, it was very helpful right now.
But I have to say, we use OpenAFS slighlty different.
Our cell here is not big, just 15-20 users, about 50 workstation (which
includes a CAVE) and 4 fileservers at all. We just want a filesystem
which is available from linux, windows, MacOS X, sun,.. and which is
available most times. NFS was to much a problem with stolen handles, and
so on.
With this in mind I/we want something reliable and work-efficient to
work with. OpenAFS is this solution in most parts. One setup for all
systems, ACLs and quota on every path available, one common filesystem
tree (sent out one path for the data and EVERY user can access THIS path).
HD space isn't really a big problem with cheap harddisks and PC. With
linux and a cheap software raid a 2 TB raid5 server is setup in 2 hours
for about 1200 euro. If we need more HD space for a RO copy on every
fileserver for our RW copies, we just buy some more harddisks. At all in
 our cell it is possible, just 500 GB data here in RW copies.
This in mind, I/we use the RO copies on different fileservers as a quick
and easy backup. For us it is efficient.
And yes, RO are used for data distribution, to. Most of the data isn't
changed often, so RO are useful for this, to. Especially the data for
our CAVE (vrml files e.g.) and the programs are really static and stored
on RO copies on a filesystem in the CAVE environment.

>> Because with only RO copies, I get a 1-day-backup, but I need a
>> long-term-backup with incremental backups.
> Keeping such backups in the form of online volumes is not terribly
> efficient.  Long term backups should be kept in the form of volume
> dumps, possibly compressed, and stored on disk and/or tape.  There are
> several options available for managing backups; you can use 'vos dump'
> or the backup system included with OpenAFS, and there are a number of
> third-party packages, both open-source and commercial, which offer AFS
> backup support. All of these approaches are capable of making use of
> incremental volume dumps.

Yeah, that was kind of my question, because short-term backup is easy
with RO copies.
Your answer was very helpful for the vos backup(sys) command and a small
guide for long-term backup.
As I read it correct, there could be only ONE backup volume of a RW
volume, which represent the state of the RW volume at the time it was
"vos backup(sys)"?
And there could only be one RO-Copy state of a RW volume? (yes, one RW
copy could "own" more than 1 RO copy, but with a "vos release" all RO
copies of a RW copy has the same state (except for a FS which was offline=

So my job is to search for third party backup tools and use vos dump.
I need to think about a nice efficient system. In real only the home
folders are really of interest for long time backup, maybe a streamer is
to much of hardware for this. A DVD-R could do this job, to.

> -- Jeffrey T. Hutzelman (N3NHS) <jhutz+@cmu.edu>
>   Sr. Research Systems Programmer
>   School of Computer Science - Research Computing Facility
>   Carnegie Mellon University - Pittsburgh, PA

Lars Schimmer
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