Volume spanning for virtual tape storage

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 system 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 is used. If there are no volumes mounted, the next loaded volume in the image catalog is mounted automatically.

If *MOUNTED is specified for a save operation, a new volume is automatically created when the end of the image catalog is reached.

If you allow the system to create a new volume for you, the system does the following:

• Adds a *NEW volume and inserts it at position 256 in the image catalog
• Mounts the volume in the virtual device
• Continues the save

When the system creates a new volume, the system gives the new virtual image a name. The system always inserts the new virtual image in position 256 of the image catalog. The size of the new virtual image is set to 1000000 MB with Allocate Storage (ALCSTG)(*MIN). The previous volume gets moved to an earlier position.

The following table shows an example of what happens when the system adds a new volume during a save operation to an image catalog where Vol001 and Vol002 existed before starting the save operation.