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112 Chapter 6:Network File Sharing Services
Avoid using exportfs -r
File systems being NFS exported by cluster members do not get specified in the conventional
/etc/exports file. Rather, the NFS exports associated with cluster services are specified in
the cluster configuration file (as established by cluadmin).
The command exportfs -r removes any exports which are not explicitly specified in the
/etc/exports file. Running this command will cause the clustered NFS services to become
unavailable until the service is restarted. For this reason, it is recommended to avoid using the
exportfs -r command on a cluster on which highly available NFS services are configured.
To recover from unintended usage of exportfs -r, the NFS cluster service must be stopped
and then restarted.
NFS File Locking
NFS file locks are not preserved across a failover or service relocation. This is due to the fact
that the Linux NFS implementation stores file locking information in system files. These system
files representing NFS locking state are not replicated across the cluster. The implication is that
locks may be regranted subsequent to the failover operation.
6.2 Setting Up a High Availability Samba Service
Highly available network file services are one of the key strengths of the clustering infrastructure.
Advantages of high availibility Samba services include:
• Heterogeneous file serving capabilities to Microsft
®
Windows™ clients using the CIFS/SMB pro-
tocol.
• Allows the same set of filesystems to be simultaneously network served to both NFS and Windows
based clients.
• Ensures that Windows-based clients maintain access to key data, or allowed to quickly reestablish
connection in the event of server failure.
• Facilitates planned maintenance by allowing the transparent relocation of Samba services to one
cluster member, enabling administrators to fix or upgrade the other cluster member.
• Allows the setup of an active-active configuration to maximize equipment utilization. More details
on active-active configurations appear below.