dbed_vmsnap - create or resynchronize a snapshot image of an Oracle database.

dbed_vmsnap -S ORACLE_SID -f SNAPPLAN
-o snapshot [ -F ] | resync

Veritas Storage Foundation. To determine whether this product is installed on the system, enter:

 rpm -qa | grep VRTSdbed

The dbed_vmsnap command is used on the primary host and creates a snapshot of an Oracle database by splitting the mirror volumes used by the database. The command can also resynchronize the split images back to the current database image. You can use the snapshot image on either the same host as the database or on a secondary host provided storage is shared by the two hosts. The file containing the snapplan specifies the snapshot scenarios (such as online, offline, or instant). For Oracle RAC database(*), the dbed_vmsnap command can be run on any Veritas Cluster Volume Manager node.

The snapshot image created by dbed_vmsnap is a frozen image of an Oracle databasea\k:^XXs datafiles. You can choose whether to include archive log volumes in the snapshot. dbed_vmsnap ensures that a backup control file is created when the snapshot database is created, which allows for complete data recovery, if needed.

When the SNAPSHOT_MODE parameter is set to online in the snapplan, dbed_vmsnap puts the tablespaces into backup mode when the snapshot is created. After dbed_vmsnap finishes creating the snapshot, it takes the tablespaces out of backup mode, switches the log files to ensure that the extra redo logs are archived, and then creates a snapshot of the archived logs. If SNAPSHOT_MODE is set to instant, dbed_vmsnap will create a snapshot regardless of whether the database is up or down, and will not put the tablespace into backup mode. In this case, the snapshot of the archive log is not needed. However, the online redo logs are required for creating a clone database. If SNAPSHOT_MODE is set to offline, online redo logs are required and the primary database needs to be down when the snapshot is created.

If the primary and secondary hosts specified in the snapplan are different, the volume snapshot will be put into a disk group and the disk group will be deported.

The snapshot functionality is useful if you want to use a secondary host for backup or a clone database for off-host processing work (such as decision-support analysis and report-generation operations, for example).

The Veritas Database FlashSnap functionality provides both snapshot status information and snapshot database status information for various stages of snapplan and snapshot procedures. You can obtain both the snapshot status and the database status from the command line using the dbed_vmchecksnap command with the -o list option. The snapshot status and database status information may also appear in error messages. For a complete list of status values, see the Veritas Storage Foundation: Storage and Availability Management for Oracle Databases Guide, Appendix C.

You can use Database FlashSnap commands in a high availability (HA) environment. See the NOTES section below for details.

The following options are supported:

-S ORACLE_SID	Specifies the name of the Oracle database for which a snapshot image will be created.
-f SNAPPLAN	Specifies the name of the snapplan for the ORACLE_SID instance.
-o snapshot [ -F ] | resync	Specifies whether to create a snapshot or synchronize the snapshot image with the current database image. Using the -F option with -o snapshot prepares the volumes for being snapshot and forces snapshot creation. The -F option can be used after a snapshot operation has failed and the problem was fixed without using Veritas Storage Foundation for Oracle commands. (That is, the volumes were synchronized without using Veritas Storage Foundation for Oracle commands.) In this situation, the status of the snapplan will appear as unavailable for creating a snapshot. The -F option ignores the unavailable status, checks for the availability of volumes, and creates the snapshot after the volumes pass the availability check. After the snapshot is created, dbed_vmsnap returns values you will need to run dbed_vmclonedb. These values include the snapshot disk group, the snapplan name, and the server name of the primary database. Make a note of these values so you have them when running dbed_vmclonedb.

* Real Application Clusters (RAC) Considerations

RAC is not supported on some SF products/configurations. For details please refer to the Veritas Storage Foundation: Storage and Availability Management for Oracle Databases Guide.

dbed_vmsnap must be run as the Oracle DBA user. The superuser cannot use this command to create a snapshot, since there is no guarantee that the database will be in a consistent state.

Before the Oracle DBA user can use this command, however, the system administrator needs to prepare Veritas Volume Manager persistent FastResync on the existing database volumes and assign disks for snapshot volumes.

The dbed_vmsnap command runs without interaction from the user.

It is recommended that you maintain different snapplans in a directory. After a snapplan is created, run the dbed_vmchecksnap utility to validate it. If a snapplan is modified or changed, you must revalidate it by running dbed_vmchecksnap.

dbed_vmchecksnap(1M), dbed_vmclonedb(1M), vxsfadm-oracle-flashsnap(1M)

Veritas Storage Foundation: Storage and Availability Management for Oracle Databases Guide

Veritas Storage Foundation for Oracle RAC Installation and Configuration Guide