Networker

Re: [Networker] tapes and block size

2004-07-27 03:58:54
Subject: Re: [Networker] tapes and block size
From: Davina Treiber <Treiber AT HOTPOP DOT COM>
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Date: Tue, 27 Jul 2004 08:57:28 +0100
Howard Martin wrote:
When I tried this with IBM LTO Ultrium 1 drives I found no noticable
improvement in speed. If I remember correctly I had an entry in st.conf
for LTO and changed the block size there. There has been at least on other
mail on this list that confirmed that there was no improvement with
increasing block size.

st.conf is NOT the key to setting block sizes, it is done by setting
NetWorker environment variables.

In most cases as you say there is no benefit in changing block sizes.
There are a couple of exceptions:
(1) In order to make Unix and NT systems use the same block size in a
heterogeneous environment. Sometimes this is done because there are
still some poorly written SCSI drivers on NT that do not allow block
sizes to be increased beyond 64KB. An exaqmple is some Compaq/HP OEM cards.
(2) In a tape SAN environment the latency of the SAN can mean that a
larger than normal block size will increase performance.

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