ADSM-L

Re: Client Compression

2000-05-10 20:15:49
Subject: Re: Client Compression
From: "Mr. Lindsay Morris" <lmorris AT OPENMIC DOT COM>
Date: Wed, 10 May 2000 20:15:49 -0400
Several authoritative sources tell me that hardware compresssion does NOT expand
already compressed files.  Though software compression (as on the *SM client)
very likely WILL increase the size of, say, a gzip file, compression on the tape
drive itself will NOT.

Hope this helps.
Gary Ison wrote:

> Bill,
>
>         Compression is, obviously, very dependent on data type.  I have
> achieved up to 80% compression on database dumps (Sybase) with large amounts
> of blank space.  Compression of already compressed files can result in
> backup failures unless you use the "compressalways=yes" option because
> compression may actually increase the files' size.  It will reduce the
> network volume, but it can be client CPU intensive to compress the data and
> may result in somewhat slower backup speeds.  I have heard reports that
> decompression is more efficient than compression, but haven't tried to
> verify them.  There is also the issue of hardware compression on tape
> volumes - the same as compressing a compressed file; it may grow.
>
>         Most of my clients do compression because we bill them for our TSM
> service based on the amount of data transferred.  Compression gives them
> some relief when paying their bill.
>
>         Gary L. Ison
>         Governor's Office for Technology
>         101 Cold Harbor Drive
>         Frankfort, Ky.   40601
>         Phone:  (502) 564-8724
>             Fax:  (502) 564-6856
> E-mail: Gary.Ison AT mail.state.ky DOT us <mailto:Gary.Ison AT mail.state.ky 
> DOT us>
>
> -----Original Message-----
> From:   Bill Sherrill [SMTP:billsh AT US.IBM DOT COM]
> Sent:   Wednesday, May 10, 2000 10:23 AM
> To:     ADSM-L AT VM.MARIST DOT EDU
> Subject:        Client Compression
>
> Does anyone have any numbers for Client Side compression?  Because of
> network throughput, we are looking at setting compression on the client.
>
> Thanks,
> Bill Sherrill
> Analyst International Corp.

--
Mr. Lindsay Morris
Mr. Lindsay Morris
Certified: AIX,ADSM, TSM, HACMP,SP
Gresham Enterprise Storage
lmorris AT openmic DOT com
606-253-8000
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