Are you talking about reading an existing tape, or writing to a new tape? When reading, you can read any series of data sets on the tape in any order you want. It is more "efficient" to read them in ascending order because it reduces the tape needed to "seek" to the next data set (tape being serial in nature). If you are writing to a tape, you must write in ascending sequence, not skipping any numbers. You cannot write file 1, then file 7, then file 2 because tape is sequential.
I don't know of any manuals which explicitly says the above. It is just logic based on knowing that tape is a sequential media. And, in my case, having some knowledge of the CCWs available on most tape devices. === Responding to a subsequent question, you will need to manually adjust the tape sequence number in order to "add a new file to the end". For our backups, we use software from Rocket Software called DBS. Basically we just tell it the type of tape cartrige we have and the volumes which need to be backed up, along with some other stuff, and it generates our JCL for us. It was originally written by Open Tech software, who were acquired by Rocket fairly recently. *http://www.rocketsoftware.com/products/rocket-dasd-backup-supervisor <http://www.rocketsoftware.com/products/rocket-dasd-backup-supervisor>* We also use the same software at the DR site because DBS keeps a "data base", which we keep on a specific volume. Using this "data base" and giving the software the addresses and volsers of the DR DASD to which to restore, DBS generates all the restore JCL. The only volume we restore "by hand" is the volume containing the "data base", which also contains the DBS software libraries. A "SETPROG APF,ADD,DSN=...,VOL=..." on the DR floor system and were golden. Once this process starts up, we basically play solitaire on the PCs. It is so easy that we only have a single sysprog start up the restores. He works alone for the first 5 or 6 hours of the DR test, doing restores. While doing the restores, DBS is smart enough to generate JCL which restores the volume in the order in which they exist on the tape. So there is not a lot of unneeded tape mounting and positioning. It is a _nice_ package! If you get it, look at their "Tape Copy" too. We use it to back up virtual 3420 tapes onto physical 3592J tapes. And then use those tapes to populate the VTS at DR with the 3420 tape data. TapeCopy is smart enough to dynamically adjust the TMC and catalog at the DR site as it does this. Again, a very good product which originated with Open Tech. On Tue, Jun 3, 2014 at 1:57 PM, Pfister, Nathan < [email protected]> wrote: > I have a question about tape labels. On my DD for a tape, when I code the > Label, I understand that the one parameter is the location/sequence on the > tape...my question is do these have to be sequential? I.e. 1, 2, 3, 4, 5. > Can I instead use 1, 2, 3, 4, 20 and still have it be recognized? Also, > if there is an answer to this available in the manual could someone kindly > point me to the right section of the right manual? > > Thanks; > > Nathan Pfister > Senior Systems Programmer > WSSC Water > [email protected] > > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > -- There is nothing more pleasant than traveling and meeting new people! Genghis Khan Maranatha! <>< John McKown ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
