(The title is a bit strong, on purpose)
LWN links to an article describing how to provide robust clustered storage with Linux and GFS.
While explaining how to setup GFS can be nice, the incentive made me jump.
The author writes:
Load balancing is difficult; often we need to share file systems via NFS or other mechanisms to provide a central location for the data. While you may be protected against a Web server node failure, you are still sharing fate with the central storage node. Using GFS, the free clustered file system in Linux, you can create a truly robust cluster that does not depend on other servers. In this article, we show you how to properly configure GFS.
In case you don’t know, GFS is not exactly a “clustered storage”. It is more a “shared storage”. You have one storage, and several clients accessing it. You have one storage array, compared to the NFS case, where you have one central server for the data. But what is a storage array except a special (and expensive) kind of server ? You don’t depend on other servers, but you depend on other servers ? How is that supposed to be different ?
Conceptually, a clustered file system allows multiple operating systems to mount the same file system, and write to it at the same time. There are many clustered file systems available including Sun’s Lustre, OCFS from Oracle, and GFS for Linux.
OCFS and GFS are the same class of file systems, but Lustre is definitely out of league and would, actually, provide a truly robust cluster that does not depend on other servers. Lustre is a truly clustered filesystem, that distributes data on several nodes such that losing some nodes don’t make you lose access to the data.
With the incentive given by the author, and considering he lists Lustre as an example, I would actually have preferred an article about setting up Lustre.
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