My Thoughts on OCFS2 / Understanding OCFS2 [1110]

As mentioned earlier, we have been considered networked filesystems instead of NFS to introduce into a number of complex environments. OCFS2 was one of the first candidates.

In fact, we also considered GFS2 but looking around on the net, there seemed to be a general consensus recommending ocfs2 over gfs2.

Ubuntu makes it pretty easy to install and manage ocfs2 clusters. You just need to install ocfs2-tools and ocfs2console. You can then use the console to manage the cluster.

What I totally missed in all of my research and understanding, and due to lack of in depth knowledge on clustered filesystems was that OCFS2 (and GFS2 for that matter) are shared disk file systems.

What does this mean?

Wikipedia defines a shared disk filesystem as being “shared by being simultaneously mounted on multiple servers.”

This essentially means that the storage medium is mounted on to cluster. The cluster is a collection of the clients. The storage is traditionally a SAN mount point. This means that a shared storage space is accessed at high speeds by a number of clients.

From a simplistic point of view, this is not that different from mounting the SAN point onto a server and then running an NFS server on it with all the clients mounting over NFS.

The main difference is that OCFS is distributed. There is no single point of failure (assuming that the storage medium is redundant which a SAN would be). The NFS server is a clear single point of failure.

If you do not have access to or want to use a SAN, you can also use DRBD.

NFS is described as a network filesystem and GlusterFS is described as a NAS file system.



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