Networker

Re: [Networker] Problem with Legato 6.1.3

2003-07-08 05:41:29
Subject: Re: [Networker] Problem with Legato 6.1.3
From: Stan Horwitz <stan AT TEMPLE DOT EDU>
To: NETWORKER AT LISTMAIL.TEMPLE DOT EDU
Date: Tue, 8 Jul 2003 05:40:37 -0400
On Tue, 8 Jul 2003, John Herlihy wrote:

>Hi Stan,
>
>I'm having this problem in a similar environment to yours, and was
>curious how changing these tcp settings on your Networker server has
>helped.

The kernal changes we made on Friday morning have helped, but only to a
minor degree. The problem persists where nsrd will slow down to a crawl.
nsrmmd processes fail to restart. I might be wrong, but this problem seems
to happen only when we run both our our Mirapoint SnapImage NDMP backups
concurrently.

Requests for tape mounts and unmounts take hours to complete when this
slow down condition starts.The nsrwatch, nsradmin, and nsradmin utilities
also become very slow.  We have a con call scheduled with people at Legato
later today to discuss our problems. We also spent a good deal of
yesterday working with our hardware service tech looking at our box.  Our
hardware service tech (we contract hardware maintenance out) is returning
this morning with a Solaris and Sun hardware expert to further check our
system and swap out a SCSI card to see if that helps the situation. There
are definitely a SCSI hardware issue on our server, but I do not see how
it can cause the performance decline in NSR that I see quite often.

Further, I have our two NDMP devices on the same SCSI bus. /dev/rmt/0cbn
and /dev/rmt/1cbn (Solaris 9 with a single CPU Sun Enterprise 450) and we
back up about 220GB of data (full backup) on each of our two NDMP devices
nightly (or at least we try). Both NDMP devices are attached to our backup
server, not the NDMP client so we use SnapImage. SnapImage is also
installed on our same server as the Legato server software. During periods
when this slow down occurs, the "top" utility shows low resource
utilization.

In fact, last night at about 8:30, I kicked off a backup of only ONE of
our Mirapoint message stores. Just as I am typing this, I received
notification that that backup completed completed successfully. No tape
mount requests are pending. Tape mounts are snappy now too. The nsrwatch
utility was slow to start, but not inordinantly so when I started it up a
few minutes ago. Throughput of the NDMP backup was a little faster than
previous backups. This is the first time I tried backing up only one NDMP
client at a time.

I suspect that if I move the one NDMP device from /dev/rmt/1cbn to
/dev/rmt/3cbn (which is on a separate SCSI bus) it will help aleviate this
problem and allow us to back up both our Mirapoint message stores via NDMP
and SnapImage simultaneously without causing this slow down condition.
Dumping nearly 450GB of data through one SCSI card all at once is probably
not a sensible thing to do if an option to spread the NDMP data across
multiple SCSI cards exists, as it does in my case.

So that's where the situation stands.

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