Roberto,
As Volker suggested, use the /REWIND qualifier. Since this backup is taking multiple tapes anyway, I can't think of any reason to append to any previous tape. Also, without it the use of /media=compaction will be ignored (at least for the first tape).
You stated you are using new media. I would expect that to work, but there may have been some bugs with backup from 7.1-2 with continuation volumes not being initialized. See $help backup /label for a description of what Backup will do if a label isn't specified.
Try this:
1. Before backup starts, initialize your tapes, each with a unique 6-character label (I would also put a paper label with that label printed in the slot in the tape cartridge. (What type of tape drive is this? DLT, DAT, something else? Please specify model number). The output of show device/full mka600: should provide a clue (at least in VMS versions from the last 10 years or so, I am not sure if 7.1-2 did).
2. In the backup command, use /LABEL=(label1,label2,label3)/exact_order/rewind [/tape_expiration=date] [/media_format=compaction] [/protect=(S:RWED,...)]. The combination of /label and /exact_order causes VMS BACKUP to verify that the correct tapes are used, and that all 6 characters of the label are significant. This prevents mistakes, like putting the same tape back into the drive and overwriting it with a continuation volume. /TAPE_EXPIRATION allows you to specify a date that you want to save the tape until, before allowing BACKUP to overwrite it. (This is a blade guard, and can be overridden). The /media_format /protect and /density are used when initializing and rewriting the tape headers.
3. I would use /BLOCKSIZE=32256 or 31744 instead of 32255 (which will be rounded down to the previous multiple of 512, or 31,744). This is just so the qualifier is consistent with the actual value that is used.
4. If you use list, I would recommend having it go to a file. I.e. /list=backup_lst:sngsbkp_1904.lis There is no problem with using /list while the backup is being made. Since this backup will have
5. /SAVE is default for tape save sets, but specifying it definitely causes no harm, and removes any doubt as to what is being written.
Example:
$! init tapes. This only has to be done the first time you use a tape (and define its tape label)
$! put in second tape
$ init mka300: rbf002 /own=system /prot=(s:rwed,o:rwed,g,w) /media=compaction
$! put in third tape
$ init mka300: rbf003 /own=system /prot=(s:rwed,o:rwed,g,w) /media=compaction
$! put in first tape
$ init mka300: rbf001 /own=system /prot=(s:rwed,o:rwed,g,w) /media=compaction
$
$! now do the backup...
$
$ Backup -
/BLOCK_SIZE=32256 /log /List=sngsbkp_1904.lis /rewind -
/Media=Compact /label=(rbf001,rbf002,rbf003) /exact_order -
sngs_pro.rbf; mka600:sngsbkp.1904 /Save /tape_expiration=1-jan-2011 ! example of tape_expiration
Jon
it depends
