To make Database Snapshots highly available, the snapped snapshot volume should contain more than one mirror. This makes the snapshot volumes available even if one of the mirrors gets disabled. Snapshot volumes can be mounted and the entire database snapshot is usable even if one of the mirror gets disabled. The multi-mirror snapshots are enabled via SNAPSHOT_MIRROR=<n>
in the snapplan.
Note There are no changes to the Command Line usage or arguments for the Flashsnap tools.
Note Before taking the snapshot, make sure all tagged snapshot mirrors are in SNAPDONE state.
The following sample explains the setup and the procedure for taking multi-mirror snapshots:
dbed_vmchecksnap
fails with appropriate errors.
Tag the newly added mirror with the same tag as that of the first mirror.
Assume that the volume has fastresync = on
, has dcolog = on
, and already has one SNAPDONE
mirror and is tagged with dbed_flashsnap.
# vxsnap -g dg_a addmir dg_a_vol1 alloc=dg_a03
# vxedit -g dg_a set putil2=dbed_flashsnap dg_a_vol1-03
SNAPSHOT_PLEX_TAG=dbed_flashsnap
When cloning a database using Database FlashSnap, the Oracle database must have at least one mandatory archive destination.
See Cloning a database (dbed_vmclonedb)
If no mandatory archive destination is set, dbed_vmchecksnap
results in this error message:
SFORA dbed_vmchecksnap ERROR V-81-5677 Could not find a mandatory, primary and valid archive destination for database PROD.
Please review the LOG_ARCHIVE_DEST_n parameters and check v$archive_dest.
This example shows how to establish a mandatory archive destination using SQL*Plus:
alter system set log_archive_dest_1 = 'LOCATION=/ora_mnt/oracle/oradata/PROD/archivelogs MANDATORY [REOPEN]' [scope=both];
For more information about Oracle parameters for archiving redo logs, see your Oracle documentation.