Creating, Resynchronizing, or Reverse Resynchronizing a Snapshot Database Using dbed_vmsnap
You can use the VERITAS Storage Foundation for Oracle dbed_vmsnap command to create a snapshot image of an Oracle database. The snapshot can be used locally or on another host that is physically attached to the shared storage. You can also resynchronize the snapshot image back to the primary database.
Prerequisites
- You must be logged in as the Oracle database administrator.
- You must create and validate a snapplan using dbed_vmchecksnap before you can create a snapshot image with dbed_vmsnap.
Usage Notes
- The dbed_vmsnap command can only be used on the primary host.
- If possible, do not share volumes between Oracle database files and other software.
- When creating a snapshot volume, create the snapshot on a separate controller and on separate disks from the primary volume.
- Make sure your archive log destination is separate from your Oracle database volumes.
- Do not place any datafiles, including control files, in the $ORACLE_HOME/dbs directory.
- Resynchronization speed varies based on the amount of data changed in both the primary and secondary volumes when the mirror is broken off.
- See the dbed_vmsnap(1M) manual page for more information.
Options
-S ORACLE_SID
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Specifies the ORACLE_SID, which is the name of the Oracle database, for which a snapshot image will be created.
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-f SNAPPLAN
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Specifies the name of the snapplan you are using.
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-o snapshot [-F] | resync
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Specifies whether to create a snapshot or synchronize the snapshot image with the current database image. The -F option prepares the volumes for being snapshot and forces snapshot creation.
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-o reverse_resync_begin
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Begins reverse resynchronization.
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-o reverse_resync_commit
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Commits the reverse resynchronization changes after you have verified that they are acceptable.
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-o reverse_resync_abort
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Aborts reverse resynchronization and mounts the original volumes back with the file systems that are configured to use the volume.
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To create a snapshot image on the primary host
Use the dbed_vmsnap command as follows:
$ /opt/VRTS/bin/dbed_vmsnap -S PROD -f snap1 -o snapshot
dbed_vmsnap started at 2004-04-02 14:15:27
VxDBA repository is up to date.
The database is running in archivelog mode.
A snapshot of ORACLE_SID PROD is in DG SNAP_PRODdg.
Snapplan snap1 is used for the snapshot.
If -r <relocate_path> is used in dbed_vmclonedb,
make sure <relocate_path> is created and owned by
Oracle DBA. Otherwise, the following mount points
need to be created and owned by Oracle DBA:
/prod_db.
/prod_ar.
dbed_vmsnap ended at 2004-04-02 14:16:11
To resynchronize a snapshot to your database
Use the dbed_vmsnap command as follows:
$ /opt/VRTS/bin/dbed_vmsnap -S PROD -f snap1 -o resync
dbed_vmsnap started at 2004-04-02 16:19:05
The option resync has been completed.
dbed_vmsnap ended at 2004-04-02 16:19:26
To resynchronize your database to a snapshot
Note
To run this command successfully, the mount point for the primary database must be created by and owned by the Oracle DBA user before mounting the VxFS file system.
Use the dbed_vmsnap command as follows:
$ /opt/VRTS/bin/dbed_vmsnap -S PROD -f snap1 \
-o reverse_resync_begin
dbed_vmsnap started at 2004-04-02 15:53:45
Database PROD (SID=PROD) is running.
dbed_vmsnap ended at 2004-04-02 15:54:29
To abort resynchronizing your database to a snapshot
This option is only allowed when reverse_resync_begin has been run. It is not allowed if reverse_resync_commit has been executed.
Use the dbed_vmsnap command as follows:
$ /opt/VRTS/bin/dbed_vmsnap -S PROD -f snap1 -o \
reverse_resync_abort
dbed_vmsnap started at 2004-04-02 16:16:44
The option reverse_resync_abort has been completed.
dbed_vmsnap ended at 2004-04-02 16:16:51
To commit reverse resynchronization changes
This option is only allowed after reverse_resync_begin has been run.
 Caution
Upon completion of reverse resynchronization, the content of the original database is discarded. Storage Checkpoints taken on either the original database or the clone database before or after the snapshot was created are discarded. The dbed_vmsnap -o reverse_resync_commit command cannot be undone and should be used with extreme caution.
Use the dbed_vmsnap command as follows:
$ /opt/VRTS/bin/dbed_vmsnap -S PROD -f snap1 -o reverse_resync_commit
dbed_vmsnap started at 2004-04-02 16:16:44
The option reverse_resync_commit has been completed.
dbed_vmsnap ended at 2004-04-02 16:18:56
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