ADSM-L

Re: AIX Server Configurations

1998-09-23 09:14:06
Subject: Re: AIX Server Configurations
From: Richard Sims <rbs AT BU DOT EDU>
Date: Wed, 23 Sep 1998 09:14:06 -0400
Regarding the debate over the number of 3590 tape drives per SCSI
adapter card:
You can certainly go for the "ideal" case of one drive per adapter;
but you need to consider economics, number of bus slots, and most
importantly the characteristics of your shop's processing.  If your
processing is dominated by huge files, then I/O throughput argues
for fewer drives on a chain.  But if your file systems are populated
with smallish files then there will be more time spent rummaging around
in the ADSM database, and so potential throughput is diminished.
Likewise, if your client backups are modest such that tape mounts and
dismounts dominate (which take a minimum of 30 seconds with a 3494),
then you can accommodate more drives on a chain.  And so, "it all depends":
you need to make a judgement call based upon the characteristics of your
environment.
    Richard Sims, Boston University OIT
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