RE: Tape backup strategy -- MIDRANGE-L

Some figures that may be helpful--a customer of ours did a test and got the following (amounts very rounded):

2.5GB library *YES and *LOW both compressed to 1.5GB, taking 4 minutes for *YES and 2 minutes for *LOW. *MEDIUM compressed to 750MB, taking 6.5 minutes *HIGH compressed to 650MB, taking 30 minutes

This was a single run, and probably othere things were going on, so that accounts for some variability. Nonetheless, it is obvious that *HIGH takes a very long time for not much gain in compression. I recommend *MEDIUM.

The SAVF can be restored to a V5R2 machine, BTW (set TGTRLS appropriately).

In V5R2, this compression was introduced in the QSRSAVO API. This is like tha SAVOBJ command but has no 300 object limit. This only applies to SAVFs, and only a single library's objects can be saved to a SAVF - same as SAVOBJ.

*HIGH uses the LZ1 algorithm, which is probably not as strong as the LZW of the various ZIP applications. Check the help for the DTACPR parameter.

Cheers
Vern

At 02:28 PM 10/1/2004, you wrote:

V5R3 has added a few options to compression:

Data compression

  *DEV
  *NO
  *YES
  *LOW
  *MEDIUM
  *HIGH

I took something in a save file saved with *HIGH and only got a ?17%?
further compression when I zipped it.  Use a simple *YES and zip will get
a higher ratio.  They both end up with the same size zip file.  So I
recommend the *HIGH.

Rob Berendt
--
Group Dekko Services, LLC
Dept 01.073
PO Box 2000
Dock 108
6928N 400E
Kendallville, IN 46755
http://www.dekko.com

"Jones, John (US)" <John.Jones@xxxxxxxxxx>
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RE: Tape backup strategy


Add DTACPR(*YES) to your SAVLIB commands to use compression on the save
file.  That should dramatically reduce the amount of disk space required
for the SAVF.

John A. Jones, CISSP
Americas Information Security Officer
Jones Lang LaSalle, Inc.
V: +1-630-455-2787  F: +1-312-601-1782
john.jones@xxxxxxxxxx

-----Original Message-----
From: Steve Morrison [mailto:smorrison@xxxxxxxxxxxxx]
Sent: Friday, October 01, 2004 1:28 PM
To: Midrange Systems Technical Discussion
Subject: RE: Tape backup strategy

The previous message was incomplete.

The simplest approach is to save to a savefile, on the AS/400, then save
the savefile to tape during the day. Do you have enough empty disk space
to accomplish this?

The command would be SAVLIB LIB(libname) DEV(*SAVF)  SAVF(savefile)

The save file will have to be created before you run this command.

To copy the savefile to tape use   SAVSAVFDTA SAVF(savefile) DEV(TAPxx)


Steve Morrison
Beacon Insurance
940-720-4672

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