Clustered file system

At its most fundamental level a clustered file system is a file system which is simultaneously mounted on a multiple servers. There are several approaches to clustering most of which do not employ a clustered file system. The most basic approach is to tie servers together (usually 2 or 3) to provide resilience to the applications running on those servers. However, unless servers are underpinned by a clustered file system the complexity of the underlying storage environment increases as servers are added effectively limiting this style of clustering to 3 or 4 servers for all practical purposes.

With a clustered file system this complexity is largely eliminated allowing very large numbers of servers to be clustered together. Using this approach every server has simultaneous read/write access to the files in the file system with no increase in complexity of the underlying storage infrastructure.