We have various types of data, some being very compressible (DB
dumps) and others are very much uncompressible (JPG files). So as in all
compression situations, "your mileage may vary" depending on the type of
the data. 

        Here is an example of the 2 extremes of our data when it ends up
on 3592 drives with compression:

*************************
Non-compressible data. Getting about 300GB/tape:

tsm: TSMHOST3>q vol C10077 f=d

                   Volume Name: C10077
             Storage Pool Name: X_TAPEPOOL
             Device Class Name: 3592DEV
       Estimated Capacity (MB): 297,763.1
                      Pct Util: 100.0
                 Volume Status: Full
                        Access: Read-Only
        Pct. Reclaimable Space: 0.0
               Scratch Volume?: Yes
               In Error State?: No
      Number of Writable Sides: 1
       Number of Times Mounted: 16
             Write Pass Number: 1
     Approx. Date Last Written: 12/25/04   23:40:55
        Approx. Date Last Read: 01/14/05   16:09:43
           Date Became Pending: 
        Number of Write Errors: 0
         Number of Read Errors: 0
               Volume Location: Bldg26 rack
Volume is MVS Lanfree Capable : No
Last Update by (administrator): ADMIN
         Last Update Date/Time: 08/30/05   13:17:23

***************************
Some very compressible data. Got about 1.2TB on a tape:

 tsm: TSMSERV1A>q vol A10007 f=d

                   Volume Name: A10007
             Storage Pool Name: X_TAPEPOOL
             Device Class Name: 3592DEV
       Estimated Capacity (MB): 1,334,463.3
                      Pct Util: 38.1
                 Volume Status: Full
                        Access: Read/Write
        Pct. Reclaimable Space: 61.9
               Scratch Volume?: Yes
               In Error State?: No
      Number of Writable Sides: 1
       Number of Times Mounted: 65
             Write Pass Number: 1
     Approx. Date Last Written: 02/06/05   20:55:23
        Approx. Date Last Read: 02/07/05   07:48:19
           Date Became Pending: 
        Number of Write Errors: 0
         Number of Read Errors: 0
               Volume Location: 
Volume is MVS Lanfree Capable : No
Last Update by (administrator): 
         Last Update Date/Time: 12/07/04   10:04:19


Ben



-----Original Message-----
From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU] On Behalf Of
Volker Maibaum
Sent: Monday, November 28, 2005 5:43 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: Re: 3592 Tape Compression

Thanks for the answers!
I already assumed that drive compression was on... But I find it a bit
disappointing that the compression ratio is that poor (only 1,4:1). When
you look at the data sheets for 3592 drives they always talk about 3:1
data compression.

Volker

Am Montag, den 28.11.2005, 07:15 -0500 schrieb Richard Sims:
> augment