Configuring policy for direct-to-tape backups

The server default policy enables client nodes to back up data to disk storage pools on the server. As an alternative, you can configure a policy to store client data directly in tape storage pools to reduce contention for disk resources.

About this task

If you back up directly to tape, the number of clients that can back up data at the same time is equal to the number of drives available to the storage pool (through the mount limit of the device class). For example, if you have one drive, only one client at a time can back up data.

The direct-to-tape backup eliminates the need to migrate data from disk to tape. However, performance of tape drives is often lower when backing up directly to tape than when backing up to disk and then migrating to tape. Backing up data directly to tape usually means more starting and stopping of the tape drive. Backing up to disk then migrating to tape usually means the tape drive moves more continuously, meaning better performance.

At the server command line, you can define a new policy domain that enables client nodes to back up or archive data directly to tape storage pools. For example, you can define a policy domain named DIR2TAPE with the following steps:

Procedure

Copy the default policy domain STANDARD as a template:
```
copy domain standard dir2tape
```
This command creates the DIR2TAPE policy domain that contains a default policy set, management class, backup and archive copy group, each named STANDARD.
Update the backup or archive copy group in the DIR2TAPE policy domain to specify the destination to be a tape storage pool. For example, to use a tape storage pool named TAPEPOOL for backup, issue the following command:
```
update copygroup dir2tape standard standard destination=tapepool
```
To use a tape storage pool named TAPEPOOL for archive, issue the following command:
```
update copygroup dir2tape standard standard type=archive
 destination=tapepool
```
Activate the changed policy set.
```
activate policyset dir2tape standard
```
Assign client nodes to the DIR2TAPE policy domain. For example, to assign a client node named TAPEUSER1 to the DIR2TAPE policy domain, issue the following command:
```
update node tapeuser1 domain=dir2tape
```