ADSM-L

Re: AIX Server Configurations

1998-09-21 18:08:44
Subject: Re: AIX Server Configurations
From: Andrew Swift <Andrew.Swift AT CENTRAL.COLESMYER.COM DOT AU>
Date: Tue, 22 Sep 1998 08:08:44 +1000
Hello Sherry,

Recently tested on 3494 library, with first one, then 2 drives, attached via
wide SCSI, we
noticed a 20% reduction (approx) in drive throughput, per drive.
Dropped from approx 8 - 8.3 MB/sec for a single drive, to approx 6.5MB/sec
per drive to
2 drives in parellel (true MB - 1024/1024...not 1000/1000 - some vendors may
calculate
on the 1000 byte per Kb base for convenience - don't know if IBM or ADSTAR
do).

So total throughput to 2 drives was 13MB/sec......raw, without ADSM, we can
write at 15MB/sec
which is the bus speed limitation (despite the 20MB/sec rating on bus speed,
15 is closer to what you'd get
in the real world). Based on that, 2 drives per F/W bus would not result in
the bus being the bottleneck.

Please note, however, that the above reduction in performance may better, or
worse, under different node
architectures (SMP vs non-SMP, PCI vs MCA etc).

Hope that doesn't muddy the water too much.

Andrew.

> -----Original Message-----
> From: Sherry Jackson [SMTP:Sherry.Jackson AT TORO DOT COM]
> Sent: Tuesday, September 22, 1998 5:31 AM
> To:   ADSM-L AT VM.MARIST DOT EDU
> Subject:      AIX Server Configurations
>
> We are running an AIX server with a 3494 library attached with 6 3590
> tape drives in it.  We will be purchasing 4-6 more tape drives in the
> future inside another unit.
>
> The problem we are having is the i/o slots in the RS/6000's.  The S70 is
> the only machine that can go over 15 slots, at least in the latest book
> we have.  With 10-12 tape drives, two ethernet, one ATM, one fddi and
> SSA disks attached, you can see will need at least 15 slots.
>
> Do any of you have 10+ tape drives attached to one machine and if so,
> what is your configuration?
>
> Sherry Jackson
> The Toro Company
> Bloomington, MN