Regards,
I recently had a rather unpleasant experience regarding NetWorker
(formerly DECnsr) 4.3 running on a ASE Cluster host (4.0b + patchset 5 +
ASE 1.4.1 + ASE patches) that rises some questions about nfs loopback
mounting and ASE in DEC Unix.
To properly explain what happened I unfortunately have to put in a
rather lengthy recap:
1. We decided long ago (before we knew about the no failover in
NetWorker and tapes) to put the /nsr area in a NFS service via ASE. As
long as we could use NFS loopback mounts we thought all would go well
anyway.
2. A long time passes and suddenly NetWorker stops working complaining
about a full NSR index filesystem. The indexfile was exactly 2GB and
this triggered an alarmbell knowing about the earlier limitations in
NetWorker.
This happened after upgrading to 4.0B and NetWorker 4.3. I called DEC
and claimed they had reintroduced the 2GB indexfilelimit in 4.3. (I am
the first to admit that this was a rather hasty conclusion, blush blush)
3. After some days of fruitless error searching, a DEC engineer in
Norway came up with a vital stamement (thanks to Tor Inge Lillebøe at
DEC Norway): "The /nsr area is nfs mounted". I said that it didn't
matter because the service containing the /nsr filesystem (AdvFS
fileset) was locally attached via a ASE servicename alias on the local
net interface. However, in /etc/fstab we had a line telling to mount the
/nsr area whenever possible:
service:/nsr /nsr nfs rw 0 0
4. For some reason, the area was now mounted nfs2 (showing up using
'mount|grep nsr'). I did a NetWorker shutdown and remounted the /nsr
area (umount/mount) and reassured myself that it now was a nfs3 area.
After doing that all was OK.
This leads to some questions; ubc-nfsloopback is enabled in the kernel.
The servicename is just an alias on the local interface (fta0). The ASE
service IS local. Why use nfs ?
I have always thought that loopbackmounting only was a way of specifying
different mountpoints for local disks thus avoiding nfs totally.
Could someone please provide me with some more elaborate details on how
DEC is defining loopback mounts ? (I hope that at least they use the
127.1 interface for loopbacking).
How does nfs loopback mounts work together with ASE ?
Why had the area suddenly become a nfs2 area ?
Any clues ?
--
******************************************************************
* Knut Hellebø | DAMN GOOD COFFEE !! *
* Norsk Hydro a.s | (and hot too) *
* Phone: +47 55 996870, Fax: +47 55 996495 | *
* Cellular Phone: +47 93092402 | *
* E-mail: Knut.Hellebo_at_nho.hydro.com | Dale Cooper, FBI *
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Received on Wed Dec 03 1997 - 14:24:17 NZDT