Preventing the nightly backup from disturbing the cache

[steve at rueb.com (Steve Bergman)]

Hi all,

I have a server with 4GB of memory and a workload that allows it to work 
mostly from memory without a lot in the way of disk reads.  However, 
every night the backup distrurbs that situation by reading every file on 
the system.

Is there a way to prevent this from happening?  I'd like to be able to 
tell the kernel, hey this program is going to be reading a bunch of 
files serially, so please don't cache the data.

Is that possible?

Thanks,
Steve