Creating, resynchronizing, or reverse resynchronizing a snapshot database using dbed


Creating, resynchronizing, or reverse resynchronizing a snapshot database using dbed_vmsnap
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Creating, resynchronizing, or reverse resynchronizing a snapshot database using dbed_vmsnap

You can use the dbed_vmsnap command to create a snapshot image of a 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.

Before creating, resynchronizing, or reverse resynchronizing a snapshot database, review the following information:

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

In an Oracle RAC environment, the dbed_vmsnap command can only be used on any CVM node.
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 for the dbed_vmsnap command are:

Table: dbed_vmsnap command options

Option	Description
-S ORACLE_SID	Specifies the ORACLE_SID, which is the name of the Oracle database instance, for which a snapshot image will be created. For Oracle RAC, specifies the ORACLE_SID, which is the name of the Oracle database instance on any CVM node.
-f SNAPPLAN	Specifies the name of the snapplan you are using.
-o snapshot [-F] \| resync	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.
-o reverse_resync_begin	Begins reverse resynchronization. Not supported for Oracle RAC.
-o reverse_resync_commit	Commits the reverse resynchronization changes after you have verified that they are acceptable. Not supportedfor Oracle RAC.
-o reverse_resync_abort	Aborts reverse resynchronization and mounts the original volumes back with the file systems that are configured to use the volume. Not supported for Oracle RAC.

To create a snapshot image on the primary host (single instance Oracle)

Use the dbed_vmsnap command as follows:

$ /opt/VRTS/bin/dbed_vmsnap -S PROD -f snap1 -o snapshot

dbed_vmsnap started at 2005-04-02 14:15:27 
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.
Oracle Database server is orasvr.
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 2005-03-15 10:07:10

The option resync has been completed.

dbed_vmsnap ended at 2005-03-15 10:07:21

To resynchronize your database to a snapshot

Assuming the mount point for the primary database was created and owned by the Oracle DBA user before mounting the VxFS file system, use the dbed_vmsnapcommand as follows:
```
$ dbed_vmsnap -S FLAS10r1 -f snaptst \
-o reverse_resync_begin
```
```
dbed_vmsnap started at 2009-07-30 14:06:38
SFORA dbed_vmsnap WARNING V-81-5725 After reverse_resync_commit is 
performed, you need to recreate the Authentication Password
File using the ORAPWD utility.
```
```
Database FLAS10r1 (SID=FLAS10r1) is running.
The option reverse_resync_begin has been completed.
dbed_vmsnap ended at 2009-07-30 14:12:22dbed_vmsnap started at 
2009-03-30 03:06:22
```
Mounting a storage checkpoint carried over from the volume snapshots is allowed only in a two-host configuration without the use of relocate path.

Storage checkpoints carried over from volume snapshots can be mounted before the clone database gets created (dbed_vmclonedb -o mount). Once the clone database is created (dbed_vmclonedb -o recoverdb), the checkpoints are no longer accessible since they are removed.

To abort resynchronizing your database to a snapshot

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

This option is only allowed when reverse_resync_begin has been run. It is not allowed if reverse_resync_commit has been executed.

To commit reverse resynchronization changes

Use the dbed_vmsnap command as follows:

Warning:

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. Storage Checkpoints taken before the snapshot was created are preserved. The dbed_vmsnap -o reverse_resync_commitcommand cannot be undone and should be used with extreme caution.

$ /opt/VRTS/bin/dbed_vmsnap -S FLAS10r1 -f snaptst \
-o reverse_resync_commit

dbed_vmsnap started at 2009-07-30 14:14:47
Oracle instance FLAS10r1 successfully started.
The database is not running in archivelog mode.
SFORA dbed_vmsnap WARNING V-81-5725 After reverse_resync_commit is 
performed, you need to recreate the Authentication Password
File using the ORAPWD utility.

The option reverse_resync_commit has been completed.
dbed_vmsnap ended at 2009-07-30 14:20:07

This option is only allowed after reverse_resync_begin has been run.

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