9.4. Special Notes Concerning Save and Restore

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9.4. Special Notes Concerning Save and Restore

The following are special considerations concerning save and restore that are important to keep in mind:

  • Save and restore do not check the cluster health (whether all nodes exist and are running) before executing. The user can find out what nodes were saved by looking at the messages displayed by the save operation.

  • Both the save and restore calls do a pre-check to see if the action is likely to succeed before the actual save/restore is attempted. For save, VoltDB checks to see if the path exists, if there is any data that might be overwritten, and if it has write access to the directory. For restore, VoltDB verifies that the saved data can be restored completely.

  • You should use separate directories for manual and automated snapshots to avoid naming conflicts.

  • It is possible to provide additional protection against failure by copying the automated snapshots to remote locations. Automated snapshots are saved locally on the cluster. However, you can set up a network process to periodically copy the snapshot files to a remote system. (Be sure to copy the files from all of the cluster nodes.) Another approach would be to save the snapshots to a SAN disk that is already set up to replicate to another location. (For example, using iSCSI.)