Increase number of loop devices in CentOS 5

Normally when you install a Eucalyptus node controller on a normal CentOS 5 (Xen) server it gives a warning during startup stating that you should have at least 32 loop devices. Here is how to extend the number of loop devices:

1. Increase the module limitation in the /etc/modprobe.conf
# echo 'options loop max_loop=255' >> /etc/modprobe.conf
2. Restart the server or run:
# rmmod loop ; modprobe loop

After a restart or reload of the module, the number of loop devices will be increased and the device entries in /dev will be automatically created.