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Using block-level backup and checkpoint

This method is useful for low bandwidth networks or very large data sets. You can use the block-level backup and checkpoint method to synchronize the Secondary when a backup of the data is available and a checkpoint has been started on the Primary. You do not have to use the network to transfer the data. This method does have a risk of SRL overflow.

Make sure that the SRL is large enough to contain all the writes made by the application while synchronization is in progress. For instructions on how to resize the SRL, see Resizing the SRL.

  Caution   During the process the checkpoint will overflow if the SRL fills up. To determine if the checkpoint has overflowed, issue the vxrvg cplist rvg_name command on the Primary to display the list of valid checkpoints.

For detailed instructions, see Example—Synchronizing the Secondary using block-level backup.

 To synchronize the Secondary using backup and Primary checkpoint

1. Start a Primary checkpoint using the vxrvg checkstart command:

   # vxrvg -g diskgroup -c checkpt_name checkstart \

local_rvgname

2. Perform a block-level backup of the data volumes in the Primary RVG.
3. End the checkpoint in the SRL when the backup is complete by using the vxrvg checkend command:

   # vxrvg -g diskgroup checkend local_rvgname

4. Restore the backup to the Secondary data volumes.
5. Start replication using the checkpoint after the restore on the Secondary completes:

   # vradmin -g diskgroup -c checkpt_name startrep \

local_rvgname sec_hostname

After the RLINKs are attached, the Secondary remains inconsistent until it has received all of the accumulated updates up to the checkend. While the Secondary is inconsistent, the inconsistent flag is set on the Secondary RLINK. After all updates up to the checkend have been received and applied at the Secondary, the inconsistent flag is cleared.

Example—Synchronizing the Secondary using block-level backup

This example explains how to synchronize the Secondary RVG hr_rvg on the Secondary host london with the Primary RVG on host seattle using block-level backup and checkpoint.

1. Start a Primary checkpoint on seattle:

   # vxrvg -g hrdg -c checkpt_presync checkstart hr_rvg

2. Perform a block-level backup of the data volumes in the Primary RVG.
3. End the Primary checkpoint when the backup is complete:

   # vxrvg -g hrdg checkend hr_rvg

4. Restore the backup to the Secondary data volumes.
5. Start replication using the checkpoint after the restore is complete:

   # vradmin -g hrdg -c checkpt_presync startrep hr_rvg london