Fine Tuning Linux for backup/production coexistence.

Hi,

I am running a CentOS 4 box with 4 terabytes of data on it. It houses
most of my users' data, so it is constantly being used.


I'm running the Networker 7.3.2 client on the box, as well. I have
established a seperate backup network successfully - all data is
backed up over this secondary network, and not over the production
network. The secondary, like the primary, is all GigE, so we're as
fast as we can go, there.


Even though I've made this change, machine response is VERY slow
during a backup. The CPU(s) get thrashed, since it has a lot of
calculations to do in order to perform a backup.

Sadly, there are no throttling options in Legato Networker, since its
really designed to do a backup as quick as possible. What I'd like to
be able to do is a backup of the system, without (significantly)
impacting server performance.

Now granted, I try to run backups during non business hours, but
sometimes thats imposssible. I tried to /bin/nice the save processes
on the file server, but this did not have a significant change.

Is it possible to improve the performance (without completely swapping
out the back plane?) Are there any /proc settings that might help?
Would bumping up the number of NFS processes help? How about the wsize/
rsize of the exported directories? Anything else anyone can think of?

If anyone has any thoughts, I would really appreciate it. I'm at a
loss, and I don't even see the advantage to a backup network now,
since my network is STILL impacted when a backup is running.



- Thanks,


Todd