Re: TAPE UTILIZATION NUMBERS

     Let me use an example of my 3590 tapes (will be the same as with your
     DLT tapes)

     OK, raw capacity is 10 GB (but with compression is guess-duh-mated at
     30 GB).  When the device class for the tapes was set up I DID NOT
     specify a capacity, thus the estimation of 10 GB will be used.

     Start writing to a new tape and put 6 GB of data on it but it gets
     compressed down to 2 GB.  tape shows est. cap. 10000 %Util 60

     Do this same thing again, write 6 GB of data compressed to 2 GB and
     the tape shows est. cap. 12000 %util 100

     Do this 3 more times, which writes a total compressed data of 10 GB
     and the tape shows FULL with est. cap. 30000   %Util 100

     Now one of those files expires off, thus 1/5th of the data goes away
     so the tape shows FULL  est. cap. 30000   %Util 80

     ...

     When you don't "force supply" a capacity with a device class
     definition the low capacity will be used until more data than that has
     been written to the tape, that is raw uncompressed data or in other
     words "how much disk space is required to pull this info off the
     tape".  As more data is written to the tape the capacity increases
     accordingly and the %util will be 100 ('cause it is unknown how much
     more data can be written before EOT is reached).  Once EOT is hit the
     tape will switch from "FILLING" to "FULL".  As data expires off the
     %Util will be reduced by that file's raw capacity (as compared to the
     capacity for that specific tape)

     hope this helps...

     later,
           Dwight


______________________________ Reply Separator _________________________________
Subject:
Author:  Cris.Robinson (Cris.Robinson AT libertymutual DOT com) at unix,mime
Date:    8/13/98 10:28 AM


Question: We are trying to rationalize why ADSM shows our DLT IV tapes
as full yet they are only 30-50% utilized and
the Est Capacity is ~20GB instead of 40GB?

Here is a sample of our tapepool status:



Volume, Storage Pool,   Device Class,  Est Capacity (MB), Percent
Utilized, Volume Status, Access Mode, Scratch
------------------------------------------------------------------------
------------------------------------------------------------------------
------------------------------------------------------------------------
-----------------------------------------------
-----------------------------------------------
D50201    TAPEPOOL     DLTCLASS     18214.7                 59.3
D50201    TAPEPOOL     DLTCLASS     18214.7                 59.3
Full          Read/Write             Yes
D50202    TAPEPOOL     DLTCLASS     18010.0                 55.0
Full          Read/Write             Yes
D50203    TAPEPOOL     DLTCLASS     18566.6                 45.9
Full          Read/Write             Yes
D50204    TAPEPOOL     DLTCLASS     18620.7                 28.7
Full          Read/Write             Yes
D50205    TAPEPOOL     DLTCLASS     18800.4                 9.9
Full          Read/Write             Yes
D50206    TAPEPOOL     DLTCLASS     20480.0                 6.7
Filling       Read/Write             Yes
D50207    TAPEPOOL     DLTCLASS     18450.5                 20.5
Full          Read/Write              Yes

Thanks -
CR

________________________
Cris Robinson
Senior Technical Analyst
Desktop Services Technical Support
Liberty Mutual Insurance
603.431.8400.54837
cris.robinson AT libertymutual DOT com