When you perform save and restore operations, you can use save files instead of tapes. Save files are objects of type *FILE that reside on disk. They offer faster backups than those provided by tapes because a save operation to a save file is a copy from disk to disk. In addition, they don't require operator intervention to mount the next tape when one ends.
On the other hand, save files use up (at least temporarily) space on your disk drives.
To use a save file instead of tape, you must create the save file first, using the Create Save File (CRTSAVF) command. For example:
CRTSAVF FILE(MYLIB/MYSAVF) TEXT('Save file for backups')
To save to the save file, execute the usual save command, except specify DEV(*SAVF) and the name of the save file in the SAVF parameter. Note that the SAVSYS command does not accept DEV(*SAVF). For example:
SAVLIB LIB(ACCTG) DEV(*SAVF) SAVF(MYLIB/MYSAVF)
This command saves the entire ACCTG library in save file MYSAVF in library MYLIB.
At your leisure, some time after this SAVLIB command ends, you can save the save file to tape and clear the save file, which frees precious disk space. To copy save files to tape, use the Save Save File Data (SAVSAVFDTA) command:
SAVSAVFDTA SAVF(MYLIB/MYSAVF) DEV(SYSTAP01) FILE(MYLIB/MYSAVF)
If you need to restore the ACCTG library from this tape, use the regular RSTLIB command. The system will not care that you used a save file in the process. If you can afford the space on your disk, you may be tempted to leave the save file full of data and never perform the backup to tape. In this case, the RSTLIB command would have to specify DEV(*SAVF) SAVF(MYLIB/MYSAVF). However, with this method, you do not have an external backup that you can keep in a safe place. If your disk crashes and must be replaced, the backup in the save file will be lost too.