ZCS Administrator Guide 8.0
ZCS Administrator Guide 8.0
Network Edition


Backup and Restore > Using Snapshots to Backup and Restore

Using Snapshots to Backup and Restore
You can back up and restore a server using the snapshot feature provided by the storage layer rather than using Zimbra’s backup and restore feature. Using snapshots, you can maintain a standby site if the primary site fails and reroute users to the standby site to keep operations running.
Snapshots are taken for all volumes of data and are transferred to the standby site periodically. Data volumes that are backed up using snapshots include mysql, blobs, lucene index, and redologs.
When the primary site is down, the zmplayredo command is used to bring consistency to the snapshots and to reapply any changes in data to minimize data loss across volumes
There are four volumes of data:
*
*
*
*
Sets of snapshots are taken every hour and transferred to the remote standby site. However, all snapshots are not taken at one instant and could be a second to a minute apart from each other. Also, snapshots of redologs may be taken more frequently. The sequence of events could look like:
8:00:00 - snapshot mysql
8:00:01 - snapshot blob
8:00:02 - snapshot index
8:00:03 - snapshot redolog
8:05:00 - transfer the snapshot set to remote site completed
---
8:15:00 - snapshot redolog
8:15:05 - transfer of redolog snapshot to remote site completed
---
8:30:00 - snapshot redolog
8:30:05 - transfer of redolog snapshot to remote site completed
---
8:35:00 - primary site fails
On the remote site, there are snapshots from the 8:00 set of data as well as subsequent snapshots of the redologs. They all have to be brought together so that the most recent information is available on the standby site once users are rerouted to it.
You can now run the zmplayredo command to replay changes from 8:00:00.
zmplayredo --fromTime ‘2008/10/17 08:00:00:000’
All data is brought forward to the current time and the standby site is set up and running. Data from 8:30:00 to 8:35:00 is lost but that is expected when the restore process is being carried out.
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