Re: Help Needed: Tape Backup Save Set

From: AEF (spamsink2001_at_yahoo.com)
Date: 08/17/05 

Date: 16 Aug 2005 19:56:10 -0700

Wayne Sewell wrote:
> >From: "AEF" <spamsink2001@yahoo.com>
> >X-Newsgroups: comp.os.vms
> >Subject: Re: Help Needed: Tape Backup Save Set
> >Date: 16 Aug 2005 15:58:01 -0700
>
> >Wayne Sewell wrote:
> >> >From: "AEF" <spamsink2001@yahoo.com>
> >> >X-Newsgroups: comp.os.vms
> >> >Subject: Re: Help Needed: Tape Backup Save Set
> >> >Date: 10 Aug 2005 19:52:55 -0700
> >> >Organization: http://groups.google.com
> >> >Lines: 27
> >>
> >> >
> >> >Z wrote:
> >> >> William Webb wrote:
> >> >> > If you
> >> >> > MOUNT/FOREIGN tape_device tape_label
> >> >> > You can
> >> >> > BACKUP/LIST tape_device:*
> >> >>
> >> >> If you're going to use BACKUP, let VMS mount the tape for you.
> >> >
> >> >Uh, on a v5.4-1 system I had trouble using BACKUP to mount a tape. If I
> >> >put in a tape that was not the first save set volume it would screw up
> >> >with funny characters reported as the label. Using an explicit
> >> >MOUNT/FOR made everything work fine. Ever since then I tend to do an
> >> >explicit MOUNT first, except with standalone backup, of course!
> >>
> >> This appears to be historical residue from the previous millenium. I was not
> >> able to reproduce this behavior on 7.3-2.
> >>
> >> In the following example, tape DLT038 is a continuation of a saveset
> >
> >[example omitted]
> >
> >> [...]
> >>
> >> Sure it got a warning message about not being at the beginning of the saveset,
> >> but it certainly had no problems finding the label or mounting the tape.
> >
> >
> >Another reason I like to MOUNT before I BACKUP is that I often have
> >very annoying and time-consuming problems with tape drives. Doing an
> >explicit MOUNT helps me determine just where the problem is. Waiting
> >for the load light to stop blinking before I issue any commands at all
> >also helps me determine what is causing a problem. If I just pop in a
> >blank tape and do a BACKUP ... /REWIND and there is trouble it is more
> >difficult to troubleshoot.
>
> I never, *ever* have problems with tape drives, at not least since I went from
> DAT to DLT, so I just simply have backup mount the tape every time. Never
> fails.

Once I get a good set of TLZ drives, the jobs all tend to run fine. The
problem is later when I try to restore something and it's not on the
very same drive it was made with. Often the restore will crap out
somewhere in the middle of the tape with parity errors. A given tape
may crap out at different places in different drives. I've had to do
restores of tapes, many of which were made before I came on the scene,
and I quite often get the stupid parity-error crap out routine. If it's
a case of alignment being different on different drives, WHY doesn't it
just crap out right at the beginning every time?

Other problems I have are amusing: One drive hurled the tape out a
couple of feet onto the floor! A "new" drive I recently got from
support often spits the tape right back out after I push it in.
Sometimes a tape gets stuck. Sometimes it protudes only 1 mm from the
front plate and cannot be pulled out nor can it be pushed back in.
Sometimes a tape comes out but snarled. One drive I got made a rattling
noise when I picked it up. A little screw fell out of it. This was a
drive I had just received to replace a broken one. Sometimes a MOUNT
operation takes over a minute and may or may not succeed. The tape may
work perfectly well on another drive. One recent job inited a tape,
mounted it, then BACKUP compalined that the label was incorrect. A
manual mount on the same drive showed a blank label. On another drive
the label was fine.

I am investigating switching to backups over the network, perhaps by
using NetBackup if they have something that will work on my MicroVAX
3100 Model 95's and 80's running VMS v6.1 and v6.2.

I have horror stories at previous jobs.

> >Additionally, anything that *might* cause trouble, like skipping MOUNT
> >when reading the 2nd tape volume, I prefer to avoid just in case it
> >causes a problem.
> >
> >Additionally**2, as lazy as I sometimes can be, it never bothered me to
> >have to do a MOUNT/FOR before running BACKUP. Eventually, I did get
> >into the habit of skipping the explicit MOUNT, only to have to wander
> >yet again through tape-drive headache space.
> >
> >Remember: I am the author of "I Lost It with the Tape Drive v1.0".
>
> As far as habit is concerned, I rarely issue the backup command directly
> anyway. Except for occasional quick tests to experiment with backup behavior,
> all my backups, test and production, are performed by tapesys, which
> automatically constructs the command lines on the fly from backup definition
> files. In particular, tapesys has total control of /[no]rewind, since it
> always knows when new tapes are to be started. tapesys will not even let you
> try to specify the rewind qualifier yourself.

Most of my backups are also done in batch. In such jobs I also prefer a
separate, explicit MOUNT command so I can better see just exactly what
was happening when it went bonkers. And I only have to type it once!

[...]

What is it with these tape drives? Have others had similar problems
with 4mm DAT TLZxx drives?

I think you can now see why I err on the side of extreme caution, and
why I wrote "I Lost It with the Tape Drive v1.0" (posted on
comp.os.vms). Check it out. It will give you better insight into my
frame of mind whenever I lose it with the tape drive.

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