[CentOS] boot-time NFS mount failures

Thu Apr 19 17:12:23 UTC 2012
Tilman Schmidt <t.schmidt at phoenixsoftware.de>

Hello List,

I have a problem with a CentOS 5 server running Oracle DBMS with
the transaction logs going to an NFS share on our CentOS 6/Bacula
backup server. The Oracle server has this in its /etc/fstab file:

backup:/home/backup/Oracle      /backup_nfs     nfs

The backup server, in its /etc/exports:

/home/backup/Oracle     -rw,async,all_squash,anonuid=133 cen5-db-01

This works quite well, except that when all the servers are rebooted
together (such as after a power outage) the Oracle server fails to
mount the NFS share, but goes ahead to start Oracle anyway. Oracle
then either complains that it cannot find its logs or, worse, starts
to write them to the local disk.

The last time this happened, I found a message on the console:

mount: can't get address for backup

So it seems that the failure was caused by the nameserver not being
available yet. Unfortunately that message isn't saved to any logfile,
so I cannot say if it was the same the previous times.

How can I make sure that the system startup does not proceed until
the NFS share is available and mounted successfully? From R'ingTFM
I got the impression that this should be the default behaviour, but
apparently it isn't. I don't know if hardcoding the backup server's
IP address into the Oracle server's /etc/hosts file would help, but
I would really like to avoid that, anyway.

Thanks in advance for any hints,