[mrtg] Re: Extreme numbers of MRTG Targets.

Henry Steinhauer H1STEINH at hewitt.com
Tue Jul 27 14:49:41 MEST 1999

Bruce -

There are a number of issues you need to consider with this.

I have more than 2,000 targets at this point so I have some reference point
to talk from.

1) Disk I/O - reading and writing the log files is where MRTG / Rateup fall
down.  This is were RRD tool shines.
--BUT - using SCSI disk and having the Windows NT options set for large I/O
cache help alot.
     -- Also having enough memory for the large I/O cache  :-)

2) SNMP Wait on response from the targets.
--  This is a sleeper item.  You have to wait for the response before you
can update the results  (duh).
   --   I put like items in the same cfg file making sure that slow devices
go into another cfg file.
  --  Getting the timings requires watching the scripts run as well as
looking at the log files and looking for long update times.
  --  (you look for intervals that are longer than 5 minutes when you think
you are running 5 minutes.  assumption testing).

3) Getting rid of and cleaning up old interface / targets.  These time out
and back up the process.

I run as many as 40 items are once.

Mainly by setting up scripts that issue the NT Start command for the
sibling streams.  This way I only have 4 driver scripts to play with and
can also blow them away when I have to re-boot the machine.  The other
items will stop and clean up when their normal cycle ends.  This also lets
the memory leaks go away since that is cleaned up with the started command

I also use a simple sleep command like SLEEP 5 inbetween each command to
give the system time to startup the process before starting the next one of
40 items.  It seems to help the overall process.

I am running on a dual 400 Mhz compaq and just recently upgraded to 512 Meg
of memory.

Let me know if you have questions.

Henry Steinhauer - h1steinh at hewitt.com

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