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RE: Tape backup strategy



fixed

CPC3722 message gives time the save started - message time would be end of save.

To augment my earlier post that had results from a run of 1, I have the following on a 9406-270 2248. I bracketed the SAVLIB commands with WRKSYSSTS RESET(*YES) before and RESET(*NO) after, which gives elapsed time and CPU% over the run. Also cleared the SAVFs first, to eliminate that processing-probably not too important, but maybe. CPU% in mid-90's for all compressed runs, around 30% for non-compressed.

The first library comprises mostly PFs and DTAARAs and is 67.6 MB

SAVF                 Size     Elapsed
DTACPRNO       70,270,976    00:00:08
DTACPRYES      32,530,432    00:00:18    46%
DTACPRLOW      32,530,432    00:00:18    46%
DTACPRMED      11,554,816    00:01:05    16%   3-1/2 times as long
DTACPRHIGH      6,311,936    00:02:22     9%   2     times as long

The second library comprises PGMs, source PFs, etc., and is 2,401.2 MB

SAVF                 Size     Elapsed
DTACPRNO    2,502,967,296    00:09:30
DTACPRYES   1,524,711,424    00:11:55    60%
DTACPRLOW   1,524,711,424    00:11:57    60%
DTACPRMED     741,359,616    00:42:43    30%   4     times as long
DTACPRHIGH    664,027,136    04:01:07    27%   6     times as long

Mileage varies because different types of objects compress differently - programs are not going to compress as well as text data, e.g. 7 to 24 times as long for *HIGH over *LOW, 2 to 6 times as long for *HIGH over *MEDIUM.

I guess it all depends, whether to go all the way to *HIGH. 6 times as long to save 3% does not seem worth it. Jeff's case, OTOH, seems viable.

You pays your money...
Vern

At 11:24 AM 10/4/2004, you wrote:
Hey, anything in your joblogs to indicate the start/stop time before and
after the data compression was changed?  Want to see if the new
compression slowed it down, so's as you would notice.  Just curious, not
trying to compare to anything here.  Just always hearing the saw about
performance and I want to check.

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





rob@xxxxxxxxx
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RE: Tape backup strategy






Glad to hear that. The new compression is IMPRESSIVE!


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





"Jeff Crosby" <jlcrosby@xxxxxxxxxxxxxxxx>
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RE: Tape backup strategy






> True, but it's rather tough to do hardware compression on a save file.

There are various areas where I do saves to a save file just prior to some
big batch update process.  I also do a SAVLIB twice a day of our main
database library to 2 different save files, then put these 2 save files
onto
a single tape.

After you posted your message last week about the new options on the
DTACPR
parm, I changed all these to *HIGH.  Since Friday, my disk usage has gone
from ~70% to ~52%.  And no one has complained about performance. <g>

--
Jeff Crosby
Dilgard Frozen Foods, Inc.
P.O. Box 13369
Ft. Wayne, IN 46868-3369
260-422-7531

The opinions expressed are my own and not necessarily the opinion of my
company.  Unless I say so.



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