[OpenAFS] TSM and AFS

Christopher D. Clausen cclausen@acm.org
Tue, 27 Sep 2005 21:39:45 -0500

Russ Allbery <rra@stanford.edu> wrote:
> Timothy G Flynn <tgflynn@stny.rr.com> writes:
>>  Are you using TSM as a backend for the AFS backup system or
>> are you using the normal TSM client to backup filesystems under /afs
>> ?
> Using the normal TSM client.

I assume he means the normal one with afs support, i.e. dsmafs or
dsmcafs.  These exist in the TSM 5.1 packages and seem to only want to
install on AIX 4.3.3 or 5.1.  I assume that the binaries can be copied
to newer AIX versions as needed, as mentioned on this list.

>>  Since you mention per-file backups I assumed you were doing the
>> later. But if that is the case why do you need any special support
>> from TSM ? Wouldn't /afs look like any other filesystem to the TSM
>> client (assuming the client process is running with an AFS token) ?
> Saving AFS ACLs and mount points is a requirement for us.

The TSM (AFS) client is also smart enough to NOT traverse mount points
if you do not want it to.  For instance, I have a single directory
/afs/acm.uiuc.edu/common/listvol that contains a list of all the volumes
that I actually want to backup.  I have a script that parses this and
re-writes the tsm config files to include volumes automagically based on
various criteria: /afs/acm.uiuc.edu/admin/scripts/tsm.*  I supose you
might be able to do something similar with excludes and such, but its
pretty hard to stop users from mounting volumes where ever they want.

If you just point a backup client at /afs you can have multiple files
backed up twice (or more) as most backup programs will not know about
mount points and treat this as a directory.  You might also have loops
as the programs traverse recursive mount points forever.  You can also
have the client start to traverse volumes in foreign cells, and this can
be very slow and cause serious delays in the backup.


We have not had many problems with TSM and AFS, other than the slow J40
that runs our backups and of course waiting for tapes to load during a
restore.  There were initial problems of obtaining working AIX 5.1
binaries, but someone of this list had some working ones (and will
hopefully provide 1.4 binaries as well once it is released.)  I did have
some problems when trying to backup .gconfd directories for certain
users.  TSM would dump core and terminate the running backup job.  I
have since simply excluded those files, but its something to watch out