ONCplus B.11.31.12 Release Notes (5900-1631, August 2011)

3 Known Problems and Workarounds
This section lists known problems, probable causes, and appropriate workarounds.
Problem
There is a possibility for an HP-UX 11i v3 system to experience a system hang under the following
conditions:
• An application writes a huge NFS file to a filesystem using NFS loopback mount.
• Two systems NFS-mount file systems from each other and simultaneously write huge amounts
of data to each other.
Causes
On an HP-UX 11i v3 system with NFS loopback mount enabled, there is a possibility for an
application to consume the entire file cache memory while writing a huge NFS file. This could lead
to a deadlock between the NFS client and NFS server modules.
For example, when the NFS client consumes the entire file cache, the server cannot execute any
of the WRITE requests sent by the client because of the non-availability of file cache memory. This
can result in non-availability of file cache memory for other mounted file systems on the node.
There is a high possibility for this problem to occur if the system is configured with low file cache
memory.
For example, when the filecache_min and filecache_max parameters are configured in the range
of 1% to 5% of the total physical memory.
Workaround
A possible workaround to handle this issue is to disable the use of the file cache by the NFS mount
by using “forcedirectio” NFS mount option.
NOTE: This workaround requires the current NFS file system to be unmounted.
Problem
When ONCplus B.11.31.12 is operating in the SRP environment, if the srp -stop command is
executed while there are active NFS mount points present in the SRP environment, it may hang
and a message similar to the following will be logged in the /var/adm/syslog/syslog.log
file:
vmunix: WARNING: SRP 13 shutdown called with 1 active NFS mounts. Waiting
for unmount to complete.
Cause
When the command is executed to shut down the SRP daemon, it may initiate the NFS client
shutdown while there are active NFS mount points present in the SRP environment. Due to this, the
srp -stop command may hang while waiting for the active NFS filesystems to unmount.
Workaround
• Before issuing the command, it is recommended to verify whether the NFS mount point in the
SRP environment is active, by executing the fuser -c command on the NFS mount point
from the global view of SRP.
# fuser -c /var/hpsrp/srp01/opt/nfstest
18 Known Problems and Workarounds