RE: Data compression on MRL3 tape drive

["Graap, Ken" <keg@xxxxxxxxxxxxxxxxxx>]

>Any ideas as to why we would be getting this and what it means about the
>"optimum block size"?


David - 

You probably want to specify DTACPR(*DEV) and USEOPTBLK(*YES).

This will let the tape drive do the compression, which is much faster. When
you specify DTACPR(*YES) you do a software compression. This uses the system
CPU resources to compress the data and slows down the save.

Check your tape device manual to see if it supports hardware compression.

Optimum Blocking is a hardware/software feature that allows for larger
blocking as data is moved to tape. If your tape drive supports this it can
speed up your saves too. There are some restrictions when using the optimum
block feature though. They have to do with the ability to duplicate tapes to
drives that don't support optimum blocking. Again, read the manual for
specific information related to your tape drive.

I've been using optimum blocking and hardware data compression on my
3590-B11 tape drives for several months now. It has significantly speeded up
my save processes....


Kenneth

--
********************************
         Kenneth  E.  Graap             
    IBM Certified Specialist                 
          AS/400   Professional                   
          System  Administrator                  
 NW Natural - Information Services        
           System Services                         
        503 226 4211 X5537                 
          FAX  503 721 2521                  
      keg@nwnatural.com               
********************************


-----Original Message-----
From: Leland, David [mailto:dleland@Harter.com]
Sent: Wednesday, June 02, 1999 8:56 AM
To: 'MIDRANGE-L@midrange.com'
Subject: Data compression on MRL3 tape drive

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