DDOBKIN@NYBVX1.BITNET (Daniel B Dobkin) (08/09/86)
We have a rather serious problem here that I hope someone will be able to help us with: we've just discovered that many of our weekly save tapes are unreadable by Backup, although Backup wrote them just fine. Here's what's happened: We have a command procedure which our operators use to perform full (weekly) and incremental (daily) saves. The procedure correctly initializes the first tape before BACKUP is invoked, and so someone (no names, please) made the not unreasonable assumption that BACKUP would initialize further volumes using a variant of the first volume label; the utility goes merrily along, writing data on the tape, until it needs a new tape. Now begins the fun: apparently, BACKUP does nothing to ensure that subsequent tapes are appropriately labelled when doing a write operation. Only after someone needed a file restored from the second or third tape did we discover that BACKUP complains about the tape not being ANSI-labelled. Now we're in the uncomfortable position of having a pile of tapes we can't read. Has anyone else encountered this? Obviously, we're making sure that all of our tapes get initialized before beginning our weekly saves, but that does nothing for salvaging the bum tapes we already have. Does anyone have any ideas for how we can copy the "bad" tapes to ones that are ANSI labelled? And, to satisfy myself, is this a feature? Or something that should be SPR'd? Daniel B Dobkin New York University Graduate School of Business DBD@NYBVX1.BITnet
carl@CITHEX.CALTECH.EDU (Carl J Lydick) (08/16/86)
X-ST-Status: N Topic: infovax, Entry # 3252 Message-Id: <8608090431.AA06268@csvax.caltech.edu> Date: Fri, 8-AUG-1986 13:15 EST From: Daniel B Dobkin <DDOBKIN%NYBVX1.BITNET@WISCVM.WISC.EDU> To: <info-vax@sri-kl> Subject: BACKUP tape problem > We have a rather serious problem here that I hope someone will be able to > help us with: we've just discovered that many of our weekly save tapes are > unreadable by Backup, although Backup wrote them just fine. BACKUP DOES initialize each tape in the saveset. Sometimes it initializes them WRONG. The following is, of course, only a guess, but it's the only explanation for your problem that I can think of that doesn't involve your version of backup doing something that I've never heard of it doing: Backup is known to select the wrong density for tapes other than the first in a saveset unless the default density for the drive is the density at which you're writing the tape. Given this fact, it seems possible that what's happened to you is that the tape drive was set to allow software- selectable densities, no /density qualifier was used in the mount command, a /density qualifier was used in the BACKUP command, and the density specified was not the drive's default density. In this case the first tape would be written at the density selected in the backup command, and all subsequent volumes would be written at the drives default density. If, whe you tried to read the tapes, software-selection if density were disabled, only the first tape would be readable.
randy@AMSAA.ARPA (08/18/86)
>> We have a rather serious problem here that I hope someone will be able to >> help us with: we've just discovered that many of our weekly save tapes are >> unreadable by Backup, although Backup wrote them just fine. >which you're writing the tape. Given this fact, it seems possible that >what's happened to you is that the tape drive was set to allow software- >selectable densities, no /density qualifier was used in the mount command, >a /density qualifier was used in the BACKUP command, and the density specified >was not the drive's default density. In this case the first tape would be >written at the density selected in the backup command, and all subsequent >volumes would be written at the drives default density. If, whe you >tried to read the tapes, software-selection if density were disabled, only >the first tape would be readable. All tape drives I have ever seen that work with VMS(or any VAX running any operating system) will READ a tape at the proper density, no matter what their default density is, and no matter how they are mounted. Put a tape on your drive and set it manually(or through software) at the improper density and try to read it. You will notice that the tape always will jiggle back and forth a few times when starting a read to see if it has the proper density, and when it finds what it thinks is the right one, it will change the density - watch the lights. Randy