Spanning occurs when the volumes have files that continue from one volume to the next.
When a save operation spans a volume, it pauses the save process when the current piece of media you are using runs out of space and continues the save operation on the next piece of media. In the context of backup and recovery, a volume is the media that you are using to save your data.
When you perform a save operation and span virtual images, the multivolume set of virtual images behaves just like a multivolume set of any form of actual media.
One advantage of using virtual storage for a backup operation is that if you have enough disk space, you can perform unattended backups without the use of a media autoloader or a media library.
Similar to actual devices, when you span volumes of virtual images, you can specify a volume list or specify *MOUNTED for the VOL parameter on all of the save commands. If you specify a volume list, the server mounts the volumes of virtual images when they are needed. In either case, you should allow for enough volumes to complete the save operation.
If *MOUNTED is specified the volume that is mounted will be used. If there are no volumes mounted, the next loaded volume in the image catalog will be mounted automatically.
If *MOUNTED is specified for a save, a new volume will be automatically created when the end of the image catalog is reached.
If you allow the server to create a new volume for you, the server does the following:
When the server creates a new volume, the server gives the new virtual image a name. The server always inserts the new virtual image in position 256 of the image catalog. The size of the new virtual image is set to 1,000,000 MB with ALCSTG(*MIN). The previous volume gets moved to an earlier position.
The following table shows an example of what happens when the server adds a new volume during a save to an image catalog where Vol001 and Vol002 existed before starting the save.
| Index | Volume Name | Virtual image name | Volume sequence number | Size | Description |
|---|---|---|---|---|---|
| 1 | Vol001 | File1 | 1 | 1000 MB | My Save 1 |
| 2 | Vol002 | File2 | 2 | 1000 MB | My Save 1 |
| 256 | GEN001 | GEN001 | 3 | 1,000,000 MB | Created on 12/31/05 15:38:29 |
