Silicon Graphics InfiniteStorage 4000 Series, Configuring And Maintaining

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152 Suspending and Resuming a Synchronous Mirroring Relationship
Suspending
and Resuming a
Synchronous
Mirroring
Relationship Use the
suspend remoteMirror
command to stop data transfer between a
primary volume and a secondary volume in a mirror relationship without disabling the
mirror relationship. Suspending a mirror relationship lets you control when the data
on the primary volume and data on the secondary volume are synchronized.
Suspending a mirror relationship helps to reduce any performance impact to the host
application that might occur while any changed data on the primary volume is copied
to the secondary volume. Suspending a mirror relationship is particularly useful when
you want to run a backup of the data on the secondary volume.
When a mirror relationship is in a suspended state, the primary volume does not make
any attempt to contact the secondary volume. Any writes to the primary volume are
persistently logged in the mirror repository volumes. After the mirror relationship
resumes, any data that is written to the primary volume is automatically written to the
secondary volume. Only the modified data blocks on the primary volume are written
to the secondary volume. Full synchronization is not required.
NOTE
If you suspend a remote mirror that is set up in the Write consistency mode,
you suspend all remote mirrored pairs within the group. You can then resume mirror
operations for any of the individual remote mirrored pairs that are in the group.
This example shows the
suspend remoteMirror
command:
c:\...\sm X \client>smcli 123.45.67.88 123.45.67.89

-c “suspend remoteMirror primary Jan_04_Account

writeConsistency=false;”
The
writeConsistency
parameter defines whether the volumes identified in this
command are in a write-consistency group or are separate. For the volumes in a
write-consistency group, set this parameter to
TRUE
. For the volumes that are not in a
write-consistency group, set this parameter to
FALSE
.
This example shows how to use the command in a script file:
suspend remoteMirror volume Jan_04_Account

writeConsistency=false;
The mirror relationship remains suspended until you use the
resume
remoteMirror
command to restart synchronization activities. This command
restarts data transfers between a primary volume and a secondary volume in a mirror
relationship after the mirror has been suspended or unsynchronized.
This example shows the
resume remoteMirror
command:
c:\...\sm X \client>smcli 123.45.67.88 123.45.67.89

-c “resume remoteMirror volume Jan_04_Account

writeConsistency=false;”
The
writeConsistency
parameter in this command operates the same as in the
previous command.