High CPU on multiple syncs on Win2K

jw schultz jw at pegasys.ws
Fri Aug 23 10:18:01 EST 2002

On Fri, Aug 23, 2002 at 08:31:35PM +0200, bart.coninckx at watco.be wrote:
> Hi all,
> Allow me to quickly sketch our backup situation: we have about 40 sites. On
> each site there's a Rsync client on an NT machine (Cygwin). In the main
> site we have a huge Win2K fileserver which acts as a Rsync server. I'm
> doing tests now with syncing the volumes of several Netware servers on the
> sites (to which the Rsync NT clients have a mapping) to the Win2K server.
> Initially we wanted to put a Rsync server on each site, but for some
> unknown reason the Rsync daemon does not want to use mappings to a Netware
> volume in its modules.
> Right now I'm doing about 10 syncs at the same time. What I'm seeing now,
> is that for every Rsync session that's initiated towards the Rsync service
> on the Win2K server, a seperate Rsync.exe is spawned. Each Rsync uses up to
> 20% CPU util. Obviously, the machine is constantly running at 100% CPU. Not
> desireable, since I want to add yet another 30 sites!
> Do you people think that if we would use a Linux server instead of a Win2K
> server, the CPU would be less burdoned?

There are so many factors i couldn't even start.  It is
possible changing OS for the server would help as linux has
historically been more efficient at disk I/O in the general
case but as i haven't done comparisons and have no NT or
W2K servers to even try.  I recall there being a patch to
preserve ACLs in NT-NT rsync so there may be a functional
benefit to sticking with an NT server (yuck!).

Some things that would help in evaluation would be the
rsync command-line and the disk configuration (are you running
RAID, what level and HW vs. SW, etc), approximate file counts
and size, and it also might help if we knew if the overloaded
server were low powered.

As a start i would check to be sure that you aren't using
the --checksum option unnecessarily.  That was apparently the
problem the last time someone reported excessive load.
Also, don't run software RAID-5.

The other thing that would be worth doing is to manage the
load better by reducing the number of simultaneous

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	J.W. Schultz            Pegasystems Technologies
	email address:		jw at pegasys.ws

		Remember Cernan and Schmitt

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