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.
