File System Tuning

Some of the default kernel paramaters for system performance are geared more towards workstation performance that file server/large disk io type of operations. The most important of these is the "bdflush" value in /proc/sys/vm/bdflush 
These values are documented in detail in /usr/src/linux/Documenation/sysctl/vm.txt. 

A good set of values for this type of server is: 

echo 100 5000 640 2560 150 30000 5000 1884 2 > /proc/sys/vm/bdflush

(you change these values by just echo'ing the new values to the file. This takes effect immediately. However, it needs to be reinitilized at each kernel boot. The simplest way to do this is to put this command into the end of /etc/rc.d/rc.local) 

Also, for pure file server applications like web and samba servers, you probably want to disable the "atime" option on the filesystem. This disabled updating the "atime" value for the file, which indicates that the last time a file was accessed. Since this info isnt very useful in this situation, and causes extra disk hits, its typically disabled. To do this, just edit /etc/fstab and add "notime" as a mount option for the filesystem. 

for example: 

/dev/rd/c0d0p3          /test                    ext2    noatime        1 2

With these file system options, a good raid setup, and the bdflush values, filesystem performace should be suffiecent. 

The disk i/o elevators is another kernel tuneable that can be tweaked for improved disk i/o in some cases.