Networker

Re: [Networker] tape drive hardware compression a bad thing?

2003-01-30 03:00:25
Subject: Re: [Networker] tape drive hardware compression a bad thing?
From: "Tarjei T. Jensen" <tarjei.jensen AT KVAERNER DOT COM>
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Date: Thu, 30 Jan 2003 03:00:29 -0500
Jim Lane wrote:

>actually
>I have a couple of large NetWare boxes that seem to backup quite slowly
>so maybe software compression would improve them.

Only if you are NOT using automatic compression on the netware server.

Networker on netware have enormous problems with files which are already
compressed. It really eats CPU cycles and backups will be sloooooowwww.

You should also be weary of using gigE (gigabit ethernet) on the networker
server with netware clients because the card/ip stack might have problem
with tcp windows sizes as small as those networker uses on netware. If the
data rate drops to around 25KB/s you have that problem. To date I have only
observed this problem on old SGI gigE cards.

We estimate that our netware server volumes consist of around 80%
compressed files. The rest is in daily use and hence uncompressed.

We use no compression on the netware servers, but every other server does
client compression. It is a effective way of offloading the networker
server and it reduces the load on the network. It can mean that you don't
need multiple gigE interfaces on the server.


greetings,

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