John,

If you have compression set at the client then the tape drive is only getting
20G of data (even although when that 20G is decompressed it will be more).

To see how much compression you are getting look in the dsmsched.log on the
client.  Or, turn off the client compression and change to using the compressed
device class (if you aren't already).   Then you should see the tapes with more
that 20G on them.  I recently did this at a client site and went from 5G on
Magstar MP tapes to 40-60G !!!  This was Oracle data which seems to compress
very well.

regards,

Stuart Robertson
Unitech Open Systems Scotland













"Doherty, John (ANFIS)" <jdohe1 AT ANFIS.CO DOT UK> on 14/02/2000 09:45:10 AM

Please respond to "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>



  To:          ADSM-L AT VM.MARIST DOT EDU

  cc:          (bcc: Stuart Robertson/Edinburgh/Unitech)



  Subject      ADSM/9840 compression problem
  :







Hi folks, we have recently installed StorageTek 9840 drives and each tape
has the capacity to hold 20GB native up to 80GB compressed.  We thought this
an ideal medium for ADSM storage.  I had set the device classes up to
accommodate 60GB (err on the catious side, 3:1 compression) with compression
set to yes.

We have tapes filling up at 19-21GB !!

Anyone experiencing this or could they give me any help on why this would be
the case?

Thank you in advance

> John Doherty. Tel:   +44   (0)   141 275 7793
>               Fax:  +44   (0)   141 275 9199
>               Email: JDohe1 AT Anfis.co DOT uk
>
>       Technical Specialist, Storage Management L02S
>
> Email communications are not necessarily secure and may be intercepted or
> changed after they are sent.  Abbey National Financial and Investment
> Services  does not accept liability for any such changes. If you wish to
> confirm the origin or content of this communication, please contact the
> sender using an alternative means of communication.  This communication
> does not create or modify any contract.  If you are not the intended
> recipient of this communication you should destroy it without copying,
> disclosing or otherwise using its contents.  Please notify the sender
> immediately of the error.
>
> ABBEY NATIONAL FINANCIAL AND INVESTMENT SERVICES plc
>         Registered Office Abbey National House 287 St Vincent Street
>         Glasgow G2 5NB United Kingdom Registered in Scotland No 159852
>