S211KENO@HTIKHT5.BITNET (Kees Noyens KUB-DRC) (12/03/86)
$ MOUNT/REBUILD can take about 15 minutes for all our disks after a crash. In trying to speed up my SYSTARTUP.COM I'm considering $ MOUNT/NOREBUILD for al our disk-devices (in a 4 VAX cluster). and doing $ SET VOLUME/REBUILD in a batch-job at night. We don't care about inaccurate disk-quota's or unavailable free space for some time. Are there any undocumented penalties to do this ? Is there anyone who has experience with MOUNT/NOREBUILD ? --------------------------------------------------------------------------- Kees Noyens Tilburg University The Netherlands
LEICHTER-JERRY@YALE.ARPA.UUCP (12/09/86)
$ MOUNT/REBUILD can take about 15 minutes for all our disks after a crash.
In trying to speed up my SYSTARTUP.COM I'm considering
$ MOUNT/NOREBUILD for al our disk-devices (in a 4 VAX cluster).
and doing $ SET VOLUME/REBUILD in a batch-job at night. We don't care
about inaccurate disk-quota's or unavailable free space for some time.
Are there any undocumented penalties to do this ? Is there anyone who
has experience with MOUNT/NOREBUILD ?
This is exactly what we do here at Yale. It works fine, and is in fact
exactly the kind of thing MOUNT/NOREBUILD and SET VOLUME/REBUILD were meant
for.
BTW, the REBUILD here has nothing to do with disk quotas - it makes sure the
allocation bitmaps are up to date. (Disk clusters and file headers are pre-
allocated and cached. If the system crashes, the on-disk version of these
bitmaps - which are completely separate - will be stale, though in a harmless
way - they will show as allocated some blocks/file headers that are actually
free.) Quota information is maintained in QUOTA.SYS. It, too, is cached and
my not be up to date, though in this case the errors could go in either
direction. I don't believe either MOUNT/REBUILD or SET VOLUME/REBUILD update
the quota files - you have to use the REBUILD command of the DISKQUOTA
utility.
The way we do it is to have SYSTARTUP, which mounts all volumes /NOREBUILD,
submit a cleanup job for 2:00 AM (using /AFTER:"TOMMOROW+2"). The cleanup
does the SET VOLUME/REBUILD's and DISKQUOTA REBUILD's for all the disks. The
only thing to watch out for is that if you have multiple re-boots in one day,
the job runs more than once. This is rare enough, and harmless enough, that
we just watch for it and get rid of the extras by hand. You could be more
clever. Also, in a cluster, you have to be a bit more clever.
-- Jerry
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