onbar clones

I'm stumbling my way through setting up onbar and everything is good except for cloning the database archive I backed up to disk onto a tape. Logs are going to 1 tape drive and the database is going to disk. Perhaps what I'm trying to do is not even possible, but I want to store the database archive on the same tape that holds our regular system backups (Different tape drive from the one used for logs). I was told this would be possible, but I've also been told wrong before by the person that told me that. I'm doing everything from shell scripts (AIX 4.3; Informix 7.31.UC5). I had wanted to simply backup the disk space that held the archive, but soon found out that as soon as I relabel the disk device to make a new backup, ism forgets about the volume which was previously stored there, making a restore from tape futile (as far as I can tell). If I can't clone directly to the same tape used for backups, can I just back up the raw files and somehow trick ism into accepting the volume label when I restore it? I really don't want a tape change in the middle of the backups. - Danny