ADSM-L

Re: ADSM versus Arcserve and Backup Exec

1998-09-16 05:25:26
Subject: Re: ADSM versus Arcserve and Backup Exec
From: Gene Mangum <gmangum AT UMICH DOT EDU>
Date: Wed, 16 Sep 1998 05:25:26 -0400
On Tue, 15 Sep 1998, David Hendrix wrote:
> We had a situation with one puny C20 with 256MB of memory where they had
> architected the application to write images files (50K to 200K each)
> into one single directory.  Unfortunately, they tracked around 1.5
> million files in a 90 day period.
>
> V2 client choked and so did the V3 client (heck they couldn't even ls
> the directory!).  They have rearchitected their system, and with the

I believe the extremely poor performance was due to a design problem
with JFS.   We've battled with this.   We think it's due to an in-core
i-node table being filled.   We found that when the number of files
in a single directory exceeds the size of this table (the size of the
table is computed at boot time based on the amount of physical memory)
reading i-nodes will peg the CPU and take a looooooong time.

We opened a crit-sit (critical situation) with IBM because of a new
application which will have 1.5 million files in one directory.
Their only solution so far is to either rewrite the application or
buy a Sun.

Note that plain old "ls" is not so bad, but "ls -l", which reads the
i-nodes, takes forever at 100% CPU.

--
Gene Mangum
Gene Mangum
University of Michigan Medical Center