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DSPTAP by itself will rewind the tape and should show the first item on it, since that's the default for the sequence number. If you're outputting to *PRINT or *OUTFILE, it'll search the tape and list everything, I think. If you then save something to the tape, adding it to the end, it'll search for where the *LEAVE left it and add from there. The sequence number will be incremented. This is just off the top of my head and looking at the DSPTAP parms.
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*LEAVE option in backup
The *LEAVE option does nothing to the tape. It doesn't mark it or anything. It simply leaves the tape at the spot where the last backup ended so you can write more to the tape with the tape already in place. Otherwise the tape has to read the header info at the start of the tape to see where the next place on the tape is and fast forward to it. I've used it when I've had to backup several objects or libraries "manually"; otherwise, the tape rewinds to the start. Restoring from a tape always starts at the beginning to read the header to see if the object/library is on the tape, and where it is located. The drive then fast forwards the tape and restores the object. Using *LEAVE on the backup has no effect on the restore. Tom. -
*LEAVE option in backup
can someone explain the *LEAVE option in a backup/save from what i understand, it will leave the end of the tape open from the point of the last save. at this point it should start the next back up from that point. my questions are - how do you restore from a tape that has the *LEAVE option turned on. if you do a dsptap - what will be shown? any and all comments are very welcomed fyi, i'm backing up some libraries for our developers on our test system - its going on an LTO2 tape - 825 running 5.2Comment
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*LEAVE option in backup
Not sure I can do better than the other two. But keep in mind that tape is completely a sequential media. There is no index of what is on the tape in the "headers". There are two parms that kind of go hand in hand. The End of Tape option just tells the system what to do at the end of the command. Leave it, rewind it, or unload it. The other parm is the Sequence #. Our daily B/U saves security info, config. info, several groups of libraries (multiple SAVLIB cmds for checkpoint reasons), and some IFS directories. The SAVSECDTA has SEQNBR(1) ENDOPT(*LEAVE), the rest of the commands have SEQNBR(*END) ENDOPT(*LEAVE) except the last uses ENDOPT(*UNLOAD). The SEQNBR(1) means write this file as the first file on the tape, right after the VOL label. ENDOPT(*LEAVE) prevents the tape from rewinding. The intervening SEQNBR(*END)s say add this after last file on tape. If we didn't use ENDOPT(*LEAVE) - default is *REWIND - the tape would rewind to the beginning. Then next command with SEQNBR(*END) would have to read through all the files on the tape to get to the last tape-mark in order to add the next file to it. ENDOPT(*LEAVE) saves that time. [With newer tape drives, that search time is becoming less significant.] The ENDOPT(*UNLOAD) on the last command is self-expanitory. Hope this helps. JCComment
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