[Info-vax] strange backup behavior

[B Hobbs]

On Aug 8, 9:42 am, AEF <spamsink2... at yahoo.com> wrote:
> On Aug 8, 9:07 am, sapienzaf <sapie... at noesys.com> wrote:
> > On Aug 7, 11:55 pm, David J Dachtera <djesys... at spam.comcast.net>
> > wrote:
>
> > > The OP may be looking for info relating to "fast skip".
>
> > I'm sure this is an emulation problem.
>
> > He's running Charon-VAX which makes OpenVMS think the SDLT tape drive
> > is a TK50.  I don't believe fast skip is an option for a TK50, and
> > furthermore he's running VAX/VMS v7.1 which (IIRC) does not have the
> > $SET MAGTAPE/FAST_SKIP command.
>
> But the tape must be being rewound between each BACKUP save operation.
> It appears that /VERIFY is not present. Perhaps he is MOUNT-ing and re-
> MOUNT-ing between each BACKUP operation? We need to see his command
> procedure.

In the procedure, allocate the tape drive, mount/foreign the tape,
position to the end, loop thru the backups, dismount/nounload the
tape, mount, directory of the files, dismount/nounload, deallocat,
exit procedure.  No, the tape is not mounted and dismounted between
backup steps.  There are only two pairs of mount and dismount, one
pair as /foreign for the backups, one pair without /foreign for the
directory list.

The backup procedure is 36 blocks, I'll post the complete procedure if
requested.  The log files range between 300 and 35,000 blocks, I think
I'll be butchering those as needed.

I only *suspect* the tape is rewinding between backup commands, but I
can't think of anyway to confirm this except the amount of time the
marker files take to backup.  Tell me again why cartridge tapes are so
much better than nine-track tapes where one can actually observe the
tape rewinding between backup steps?  :-(

> To the OP: Why are you not using /IMAGE instead of /FAST [000000...]?
> Why are you making both a journal file and listing file of each save
> set?

The procedure loops thru the disks, executing pretty much the same
backup command on each disk.  There is an embedded symbol in the
backup command that shows up as an empty continuation line for most of
the disks, for some disks this symbol contains an /exclude.  /Image
ignores /exclude, it was simpler to use the same command for all
disks.  It wouldn't be difficult to change to /image for some disks,
but I didn't see much advantage from reading the documentation.

I apologize for not answering sooner, I had weekend Reserve duty and
was busy making the planet a safer place for VMS geeks
everywhere.  ;-)