Mounting a Shadow Set on Other Nodes in the Cluster

If a shadow set is already mounted on one or more nodes in an OpenVMS Cluster system, the /SHADOW qualifier is not required when you mount the same shadow set on other nodes in the cluster. For example, if DSA42 is already mounted in the cluster when a new node is brought into the cluster, you can use the following command to mount DSA42 on the new node:

$ MOUNT/SYS DSA42: volume-label logical-name

Upon receiving this command, the volume shadowing software creates the shadow set on the new node with the same members that currently exist on other nodes in the cluster.

Reconstructing a Shadow Set With /INCLUDE

Example 4-7 shows how to reconstruct a shadow set. The volume shadowing software determines which disk volumes are former members of the shadow set.

Example 4-7 Reconstructing Shadow Sets With /INCLUDE

$MOUNT /SYSTEM DSA4/SHAD=($4$DIA1,$4$DIA2,$4$DIA3) NEWDISK

%MOUNT-I-MOUNTED, NEWDISK   mounted on _DSA4:
%MOUNT-I-SHDWMEMSUCC, _$4$DIA1: (DISK01) is now a valid member
of the shadow set
%MOUNT-I-SHDWMEMCOPY, _$4$DIA2: (DISK02) added to the shadow set
with a copy operation
%MOUNT-I-SHDWMEMCOPY, _$4$DIA3: (DISK03) added to the shadow set
with a copy operation
$DISMOUNT DSA4

$
$MOUNT DSA4:/SYSTEM/SHAD=$4$DIA1 NEWDISK/INCLUDE

%MOUNT-I-MOUNTED, NEWDISK   mounted on _DSA4:
%MOUNT-I-SHDWMEMSUCC, _$4$DIA1: (DISK01) is now a valid member of the shadow set
%MOUNT-I-AUTOMEMCOPY, _$4$DIA2: (DISK02) automatically added to the shadow set
%MOUNT-I-AUTOMEMCOPY, _$4$DIA3: (DISK03) automatically addedto the shadow set

The first command in this example creates the shadow set represented by DSA4. The shadow set consists of three shadow set members: $4$DIA1, $4$DIA2, and $4$DIA3.

After all copy operations have completed, the DISMOUNT command dissolves the shadow set.

The /INCLUDE qualifier shown in the second MOUNT command triggers the MOUNT command to reconstruct the shadow set back to the way it was before the shadow set was dissolved. The MOUNT command must specify the original virtual unit name (DSA4) and at least one of the original shadow set members ($4$DIA1). The Mount utility reads the membership list on $4$DIA1 (specified in the first MOUNT command) to determine that $4$DIA2 and $4$DIA3 are also members of the shadow set.

Because the shadow set was properly dismounted, the shadow set members are in a consistent state. The MOUNT status messages indicate that the shadow set devices are added back into the shadow set without the need for copy operations.

Mounting a Former Shadow Set Member as a Non-shadowed Disk

Occasionally, you have to mount a physical shadow set member as a nonshadowed disk. By default, when a shadow set member is mounted outside a shadow set, the Mount utility automatically write-locks the disk. This provides a safeguard against accidental modification, thereby allowing the disk to be remounted into a shadow set at a later time.

To override this default behavior, include the /OVERRIDE=SHADOW_MEMBERSHIP qualifier on the MOUNT command. For example:

$MOUNT/OVERRIDE=SHADOW_MEMBERSHIP $4$DUA20: WORKDISK

This command ignores shadow set membership status and mounts a former shadow set member on $4$DUA20 as a nonshadowed disk with write access.