>
> quick question someone may have the answer to
>
> if 'vos release root.afs' is run in a schedule to update
> the RO replica's what time interval between executions is
> safe...
> ie if vos release was run every 2 mins and the previous
> vos release had not finished, what would happen if another
> vos release was started before the previous had finished.
>
> the intention is to have as near as possible real-time
> replication.
>
> any comments
First, I'll answer your question:
If a release is in progress and you attempt a second one, the
second one will fail, because the VLDB entry for the volume in
question is already locked. The first release will finish as
usual.
However, I would suggest that you don't really want to run a
release every two minutes. Among other things, that would make
it awfully hard to make any changes, or even access the RW
volume, since it would be offline for cloning a good portion
of the time. If you really must have near-real-time replication,
try something like this...
Write a script that periodically runs 'vos examine' on both
root.afs and root.afs.readonly. Examine the 'Last Update' time
for each, and if root.afs is newer than root.afs.readonly _and_
hasn't been modified for at least X minutes, do a release.
I'd set X around 30 minutes, and run the script every 5 or so.
The two 'vos examine' operations you'd be doing are considerably
less resource-intensive than the actual release, and don't take
the volume offline. Thus, you can afford to do them fairly often,
and the volume only gets released when needed.
-- Jeffrey T. Hutzelman (N3NHS) <[EMAIL PROTECTED]>
Systems Programmer
School of Computer Science - Research Computing Facility
Carnegie Mellon University - Pittsburgh, PA
