Timing Pairsplit Operations - Hitachi TAGMASTORE MK-90RD011-25 User Manual

4.3.1

Timing Pairsplit Operations

The pairsplit command terminates after verifying that the status has changed according to
the pairsplit command options (to PSUS or SMPL). If you want to synchronize the volume
pair, the non-written data (in the host buffer) must be written before you issue the pairsplit
command. When the pairsplit command is specified, acceptance of write requests to the
primary volume depends on the fence level of the pair (data, status, never, or async). Some
examples are shown below.
Instantaneous offline backup of UNIX file system:
Unmount the primary volume, and then split the volume pair.
–
Mount the primary volume (mount -rw).
–
Verify that the pairsplit is complete, and mount the secondary volume (mount -r).
–
Execute the backup.
–
Restore the volumes to their previous state, and resynchronize the volume pair.
–
Online backup of UNIX file system:
Issue the sync command to a mounted primary volume to flush the file system
–
buffer, and then split the volume pair using the -rw option.
Verify that the pairsplit is complete, and then use the fsck command to check the
–
consistency of the secondary volume file system.
Mount (mount -r) the secondary volume.
–
Execute the backup.
–
Restore the volumes to their previous state, and resynchronize the volume pair.
–
Instantaneous offline backup of Windows file system:
Execute -x umount on the PVOL, then split the volume pair with the -rw option.
–
Execute x-mount on the primary volume.
–
Make sure that the paired volume is split, then execute -x mount on the SVOL.
–
Execute backup, and unmount the SVOL (-x umount).
–
Resynchronize the volume pair and restore the previous state.
–
Online backup of Windows file system:
Issue -x sync in the state the primary volume is mounted, then flush only the file
–
system buffer. Then, split the paired volume with the -rw option.
Make sure that the paired volume is split, then execute -x mount on the SVOL.
–
Execute backup, and unmount the SVOL (-x umount).
–
Resynchronize the volume pair.
–
Note: If the primary volume is divided by LVM or partition, the control information of LVM or
partition on the primary volume is also copied to the secondary volume. In case of executing
the backup from the secondary volume, it is required to import this control information, and
to execute pairsplit with the -rw option when activating the secondary volume.
178 Chapter 4 Performing CCI Operations