If your data (or much of your data) is being compressed at the client level,
this is normal.

The ADSM server only reports the number of bytes that it writes to the tape.

If the client compresses the data before sending to the server, then ADSM
will only report the already-compressed figures.  You get little additional
compression going from the server to the tape.

Assume you get EXACTLY 2:1 compression.

If the client sends 40 GB without compressing the data, ADSM will report 40
GB, it will be compressed to 20 GB by the tape hardware, and the tape will
be full.

If the client compresses the 40 GB to 20 GB before sending it to ADSM, the
ADSM server will report 20 GB, it will not get compressed any more by the
tape hardware, and the tape will still be full!


> -----Original Message-----
> From: Reinhold Wagner [SMTP:rwagner AT ZEUNASTAERKER DOT DE]
> Sent: Tuesday, July 13, 1999 4:23 AM
> To:   ADSM-L AT VM.MARIST DOT EDU
> Subject:      3590E capacity
>
> Hi,
>
> last week we installed a 3494 library with 4 3590-E1A drives. ADSM is 4.3
> on AIX.
>
> We've done our first backup over the weekend and i see that our tapes
> are full with 18 to 32 GB.
>
> 3590-E must have a native capacity of 20 GB per tape and if I assume
> a minimum compression of 2:1 i must reach 40 GB minimum per tape!
>
> How can i examine the tapes (128/256 tracks, blocksize and so on)?
> Is there any parameter to set?
>
> TIA
>
> Reinhold Wagner, Zeuna Staerker GmbH & Co. KG