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Posted by: Bob Cozzi
Rogue Programmer
Cozzi Productions, Inc.
Chicagoland
Space/Capacity of a Tape in the tape drive
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Published: 07 Nov 2011
Revised: 23 Jan 2013 - 1667 days ago
Last viewed on: 17 Aug 2017 (3782 views) 

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Space/Capacity of a Tape in the tape drive Published by: Bob Cozzi on 07 Nov 2011 view comments(2)

As you all may know, I've had to take over some duties for a client whose primary support person passed away in September. So I'm doing things I haven't done (in some cases) for 20 years.

I'm rewriting their nightly autonomous backup and wondered if there is a way to check the open space on a tape in the tape drive. That or if I initialize it, is there a way to show its capacity? I need to know how much addition information/data I can include in the TAPE backup vs our "over the net" backup.

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Posted by: DaleB
Premium member *
Reading, PA
Comment on: Space/Capacity of a Tape in the tape drive
Posted: 5 years 9 months 10 days 23 hours 32 minutes ago

Nothing comes to mind. You could kind of kludge it from DSPTAP to an outfile (there's an API equivalent); I think you'll only need *LABELS. You'll have to build a lookup table of some kind to determine theoretical tape capacity from the density code. Hopefully there's enough to be able to tell the individual file sizes; might have to calculate from block size and number of blocks.

Try it interactively to see what all is there. Interactive DSPTAP goes one label (file) at a time, so you don't have to read the entire tape.

One thing that may complicate this, even if it all looks good, is how compression figures into it. The sizes you get from the VOL2 labels will be after compression (what's actually on the tape). You may need to go to *SAVRST to get the sizes of what was saved, though it might be close enough if you just look at what's on the system now.

Posted by: bobcozzi
Site Admin ****
Chicagoland
Comment on: Space/Capacity of a Tape in the tape drive
Posted: 5 years 9 months 10 days 3 hours 9 minutes ago

Couldn't find anything good enough to use, so I just saved what I could and waited for the Mount Next Tape message. Fortunately I didn't get it.

I did add up the block size x blocks saved and did some rough calcs using those figures--I'm saving about 1.2GB on a tape designed for up to 2.5GB so I think I'm good for now.

Thanks, Dale.