Introduction to High-Availability Clusters On Linux And Other Systems

In order for the data to be accessible to several cluster nodes, it is placed on an external SAN or NAS storage device.
The disks are normally managed using RAID 5 (using a parity disk), or RAID 1 (mirroring).
In this setup, a single disk failure will not cause the cluster to fail.
The disks are stored in a RAID device, which allows replacing faulty disks without powering down the other disks. This is called "hot-swap".
On the other hand, since the storage device is connected via a network, the server might lose access to it.
To overcome this, more then one network path may be connected between each cluster node and the storage device.

Originally written by