Total Media Capacity Question

[Wobbe_Bouma]

All,

I have the following hardware and software

Windows 2003 running on a Proliant DL380G3
Backup Exec 9.1 SP1 using a SDLT160 MSL5000 Library (1drive)

All the library slots are loaded with HP sdlt Tapes. I'm not 100% sure but I think all the tapes can store 320GB with compression (all were purchased at the same time)

The problem: When I check the properties of the tapes and go to the general tab I get different total capacities for different tapes. For example 106, 130, 149 and even 257 GB ! How can this be? Are some tapes formatted at the 110-220 format or does a tape lose capacity because of the soft write errors? If they are formatted at the wrong format how can I change this? HP tape tools?

Because of the low capacity backup exec takes tapes out of other media sets and that's not wat I want. Is it possible to setup backup exec to fail the job rather then take tapes out of other media sets?

Hope you can help because this is driving me mad!

Kind regards,

Wobbe

[Wobbe_Bouma]

Another thing I noticed is that if I goto the the "media type tab" when looking at the properties of the tape drive there is no SDLT 160 shown! Am I using the wrong drivers?

[Ken_Putnam]

Until BackupExec has written data up to the End-of-Tape marker, it really doesn't know what the capacity of the tape is.

Yes, the tapes are rated at 160GB native/320GB compressed, but 2:1 compression is a marketing thing, not an engineering thing. See http://seer.support.veritas.com/docs/199542.htm . I generally use about 1.3:1 as a rule of thumb

If you want to (for example) limit monday's job to only the tape in slot one, you can partition the library into as many "virtutal tape drives" as you like, and point jobs to each partition.

[Wobbe_Bouma]

Thanks Ken, your post helped a lot.
I've done a long erase on one of the tapes and it now reports a total capacity of 149mb and that a lot closer to the 160 then before. I guess you lose some capacity because the tape is formatted? It's a bit strange that my other MSL5000 library reports the same total tape capacity for every tape and as far as I know none of the tapes ever reached the end of the tape. But this quote from the help file could explain this "Some tape devices support the ability to read the amount of total capacity of the media that is currently loaded in the device" This library has a older type SLDT drive.
Further more your Idea of partitioning the library is probably the solution I'm looking for. Thanks again.Message was edited by:
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