we are at 4.1.5 with OS/390 2.10 on 2066-002.
we backup about 350 GB daily.
in the past we had bad performance when running with bufferpool=100000 and
regionsize = 0 (!)
what about priority/cpu and io-stress on your dasd ? 
 

          Available Space (MB): 21.200
        Assigned Capacity (MB): 21.200
        Maximum Extension (MB): 0
        Maximum Reduction (MB): 3.428
             Page Size (bytes): 4.096
            Total Usable Pages: 5.427.200
                    Used Pages: 4.265.049
                      Pct Util: 78,6
                 Max. Pct Util: 80,0
              Physical Volumes: 21
             Buffer Pool Pages: 25.000               regionsize is 512 MB !
         Total Buffer Requests: 276.035.980
                Cache Hit Pct.: 97,78
               Cache Wait Pct.: 0,00
           Backup in Progress?: No
    Type of Backup In Progress: 
  Incrementals Since Last Full: 0
Changed Since Last Backup (MB): 424,15
            Percentage Changed: 2,55
Last Complete Backup Date/Time: 11-06-2003 18.01.11


good luck !

regards

Michael Heiermann
OD1 Systembetreuung 
LINDE AG  Material Handling
Schweinheimer Straße 34
D-63743 Aschaffenburg
Tel.:   ++49 6021 99-1293
Fax.:   ++49 6021 99-6293 
e-mail:   michael.heiermann AT linde-mh DOT de




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