Achieving the Highest Levels of Parallel Sysplex Availability

152 Achieving the Highest Levels of Parallel Sysplex Availability

– SYSNAME is a new parameter on the ROOT and MOUNT statements that specifies

the particular system on which a mount should be performed. The system will then

become the initial owner of the file system mounted. The default is the current system.

– AUTOMOVE, NOAUTOMOVE, and UNMOUNT are new parameters on the ROOT and

MOUNT statements used to decide what action is to occur when the system that owns

the file system goes down. The default is AUTOMOVE. Refer to 3.15.2, “Automove” on

page 152.

򐂰 Automount policy management

Prior to shared HFS, automount policies could be system specific with a sysplex. With

shared HFS, all mounted file systems area available to all systems participating in shared

HFS; therefore the policies should be identical in the /etc/auto.master associate map files

maintained by each system.

3.15.2 Automove

Automove is a feature of shared HFS that determines how file system ownership is to be

managed if the owning system goes down. Valid options are:

򐂰 AUTOMOVE specifies that ownership of the file system automatically moves to another

system.

򐂰 NOAUTOMOVE specifies that ownership of the file system is not moved and, as a result,

the file system becomes inaccessible.

Prior to z/OS 1.4, the relocation of file system ownership was random and any of the other

shared HFS participating systems could become the new owner. z/OS 1.4 has provided new

parameters on the MOUNT statement to give an installation more control over this process:

򐂰 AUTOMOVE(INCLUDE,sysname1,sysname2,...) may be used to specify a prioritized list

of systems where the file system ownership may be moved.

򐂰 AUTOMOVE(EXCLUDE,sysname1,sysname2,...) may be used to specify a list of systems

where the file system ownership may not be moved.

򐂰 UNMOUNT specifies that the file system should be unmounted, including any file systems

mounted within its subtree.

It is recommended that the sysplex root and version HFS are designated as AUTOMOVE to

allow another system to take ownership of these file systems when the owning system goes

down.

The system-specific HFS, and other HFSs containing file systems that are managed on a

system-specific basis (/dev, /tmp, /var, /etc) should be designated as NOAUTOMOVE to

prevent change in ownership.

It is not advisable to mount AUTOMOVE file systems within NOAUTOMOVE file systems, as

the file system concerned will not be recovered after a system failure until the failing system is

restarted.

Specify NOAUTOMOVE for file systems that are mostly used by DFS™ clients. A file system

can only be exported by the DFS server on the system that owns the file system. Once a file

system has been exported by DFS it cannot be moved until it has been un-exported from

DFS.

Unplanned outages

When a system is removed from a sysplex, there is a window of time during which any file

systems it owned will become inaccessible to other systems. This window occurs while other