ADSM-L

Re: Compressed Data Grew

1997-06-12 02:45:57
Subject: Re: Compressed Data Grew
From: Christo Heuer <christoh AT ABSA.CO DOT ZA>
Date: Thu, 12 Jun 1997 08:45:57 +0200
Hi Mark,Francisco,

The compression algorithm(Ziv Lempel) ADSM uses is the same as that used in
pkzip, MVS HAC, and most likely unix as well, and yes the data will normally
grow
when trying to compress it for a second time(not a fault of ADSM).

You can look into the client option compressalways yes/no.

As far as Mark's question about the incremental backup is concerned, I'm not
sure why that is happening - doesn't sound right to me.

Regards

Christo Heuer
Johannesburg
South Africa
Christoh AT absa.co DOT za

> Hi Mark,
>
> Mark Rizzo wrote:
> >
> > ADSM Folks,
> >
> > Can anyone tell me why I keep getting the message,
> > "Compressed Data Grew" when trying to incrementally
> > backup a file that I know is NOT changing? Since I have
> > the retries set to two, it will eventually successfully
> > backup the file. These files average 600MB in size, so
> > an unnecessary retry really slows things down.
> > Any suggestions??
> >
> > The file system is static and the file modification
> > date is several weeks old. I'm running AIX 4.1.4 and
> > ADSM v2.1.5.10. I'm backing up files from a Solaris
> > 5.5 system.
> >
> > Thanks,
> > Mark Rizzo
> > DOD
>
> I too have noticed this.  I get these kind of messages/actions when
> the file has been gziped, although, I don't get this sort of messages
> when the file has been compressed through the use of UNIX compress.
> I too feel it's kind of annoying, but I have much greater problems
> with trying to integrate jfs files soft linked and hsm files that this
> sort of thing becomes rather trivial.  I just assumed that the the
> ADSM compress function was not smart enough to detect that the file
> was already compressed and that it tried to compress a compressed file
> thus making it bigger.
>
> I hope that his helps.
>
> Francisco
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