Cluster File System Independence

The cluster file system is independent of the underlying file system and volume manager. Currently, you can build cluster file systems on UFS using either Solstice DiskSuite or VERITAS Volume Manager.

As with normal file systems, you can mount cluster file systems in two ways:

• Manually--Use the mount command and the -g option to mount the cluster file system from the command line, for example:

  # mount -g /dev/global/dsk/d0s0 /global/oracle/data

• Automatically--Create an entry in the /etc/vfstab file with a global mount option to mount the cluster file system at boot. You then create a mount point under the /global directory on all nodes. The directory /global is a recommended location, not a requirement. Here's a sample line for a cluster file system from an /etc/vfstab file:

  /dev/md/oracle/dsk/d1 /dev/md/oracle/rdsk/d1 /global/oracle/data ufs 2 yes global,logging

While Sun Cluster does not impose a naming policy for cluster file systems, you can ease administration by creating a mount point for all cluster file systems under the same directory, such as /global/disk-device-group. See Sun Cluster 3.0 Installation Guide and Sun Cluster 3.0 System Administration Guide for more information.

The Syncdir Mount Option

The syncdir mount option can be used for cluster file systems. However, there is a significant performance improvement if you do not specify syncdir. If you specify syncdir, the writes are guaranteed to be POSIX compliant. If you do not, you will have the same behavior that is seen with UFS file systems. For example, under some cases, without syncdir, you would not discover an out of space condition until you close a file. With syncdir (and POSIX behavior), the out of space condition would have been discovered during the write operation. The cases in which you could have problems if you do not specify syncdir are rare, so we recommend that you do not specify it and receive the performance benefit.

See "File Systems FAQ" for frequently asked questions about global devices and cluster file systems.