Serviceguard NFS Toolkit A.11.11.06 and A.11.23.05 Administrator's Guide

Overview of Serviceguard NFS

Limitations of Serviceguard NFS

Chapter 1 9

Limitations of Serviceguard NFS

The following limitations apply to Serviceguard NFS:

• Applications lose their ﬁle locks when an NFS server package moves

to a new node. Therefore, any application that uses ﬁle locking must

reclaim its locks after an NFS server package fails over.

An application that loses its ﬁle lock due to an NFS package failover

does not receive any notiﬁcation. If the server is also an NFS client,

it loses the NFS ﬁle locks obtained by client-side processes.

NOTE Beginning with Serviceguard NFS A.11.11.03 and A.11.23.02, you

can address this limitation by enabling the File Lock Migration

feature (see “Overview of the NFS File Lock Migration Feature” on

page 11).

To ensure that the File Lock Migration feature functions properly,

install HP-UX 11i v1 NFS General Release and Performance Patch,

PHNE_26388 (or a superseding patch). For HP-UX 11i v2, the

feature functions properly without a patch.

• If a server is conﬁgured to use NFS over TCP and the client is the

same machine as the server, which results in a loopback NFS mount,

the client may hang for about 5 minutes if the package is moved to

another node. The solution is to use NFS over UDP between

NFS-HA-server cross mounts.

• The /etc/rmtab ﬁle is not synchronized when an NFS package fails

over to the standby node. This is caused by the design of NFS, which

does not keep track of the state of the rmtab. The man page for

rmtab contains a warning that it is not always totally accurate, so it

is also unreliable in a standard NFS server / NFS client

environment.

• AutoFS mounts may fail when mounting ﬁle systems exported by an

HA-NFS package soon after that package has been restarted. To

avoid these mount failures, AutoFS clients should wait at least 60

seconds after an HA-NFS package has started before mounting ﬁle

systems exported from that package.

B5140-90030.book Page 9 Thursday, August 24, 2006 9:32 AM