Veritas-bu

[Veritas-bu] question about software compression

2003-03-27 13:28:25
Subject: [Veritas-bu] question about software compression
From: jonw AT n2h2 DOT com (Jon Walton)
Date: Thu, 27 Mar 2003 10:28:25 -0800 (PST)
I have another question regarding differential SCSI busses.   The guy that
sold me our StorageTek L80 told me never to put a tape drive and a robot
arm on the same SCSI bus.   He could not give me a reason though.
Can someone comment on this?

Thanks,

Jon

On Thu, 27 Mar 2003, Donaldson, Mark wrote:

> What kind of SCSI bus?  Differential?  Two drives per bus should be OK with
> diff.  I wonder if HP is giving you excuses for poor firmware?  Be sure to
> check those drive firmware versions.
>
> Software compression is SSSSlllllooooowwwww and puts a measurable effect on
> a client if you usually use multiple streams.  In my testing, it seems the
> compression algorithm isn't that tight, a compressed image on disk will
> recompress with "compress" or "gzip" very nicely which shows the algorithm
> is pretty loose.  I don't know how well it compares to tape compression
> rates, though.
>
> Avoid software compression if you can, IMO.
> -M
>
> -----Original Message-----
> From: Marvin Blackburn [mailto:mblackburn AT glenraven DOT com]
> Sent: Thursday, March 27, 2003 11:08 AM
> To: Veritas--ListServer (E-mail)
> Subject: [Veritas-bu] question about software compression
>
>
> We may have to turn off hardware compression on our DLT8000 drives and move
> the compression to NBU.
> We currently run 3.4.3 against a P3000 ATL Library.  We have two drives on
> the same scsi bus and
> HP is telling us that this may saturate the bus and cause hardware errors.
> What kind of performance/time/media consequences should I expect.
>
>
>
> ------------------
> Marvin Blackburn
> Systems Administrator
> Glen Raven
> "He's no failure.  He's not dead yet" --William Lloyd George
>
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