13. Tuning the server

Once you get the server and workstations setup, and you begin to increase the size of the network, you may need to perform some tuning of the server.

The following items may need to be tuned:

13.1 Maximum number of files that can be opened on the server

By default, the maximum number of files that can be opened is set to 4096. You can check what the max is on your system by running:

cat /proc/sys/fs/file-max

You can change this limit by echoing a new value into that file, like this:

echo 8192 >/proc/sys/fs/file-max

You should put this command in the /etc/rc.d/rc.local file so that it runs each time the server is rebooted.

13.2 Maximum number of inodes that can be opened on the server

By default, the maximum number of open inodes is 16384. You can check what the max is on your system by running:

cat /proc/sys/fs/inode-max

You can change this limit by echoing a new value into that file, like this:

echo 32768 >/proc/sys/fs/inode-max

You should put this command in the /etc/rc.d/rc.local file so that it runs each time the server is rebooted.

13.3 Maximum number of processes that can be run on the server

On Redhat 6.0, and in kernels downloaded from kernel.org, the limit on the total number of processes is 512, and the limit on the number of tasks per user is half of that.

Since Redhat 6.1, using the standard redhat supplied kernel, the total number of process is 2560, and the max per user is 2048.

If you need to increase the limits, you will need to modify the /usr/src/linux/include/tasks.h file. The parameters to change are NR_TASKS and MAX_TASKS_PER_USER.

In all cases, the maximum value for these parameters is 4092 ( 4090 if APM is enabled ).

If you change these parameters, you will need to build a new kernel.