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Need clarification regarding selecting a shared file system for our servers . The shared space is from SAN and the servers will write to the shared file system at the same time.

One option for me is to select GFS , but I think that requires creating a cluster first and since it will be a HA cluster , I think only one server will be able to write to shared file system at the same time . My confusion here is that if I just run the cluster services without creating a cluster will I be able to configure and run GFS. Also, if I use GFS , can I write to the GFS file system from two servers at the same time.

Also would like to know what other options are available to me.

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the final line is far too open-ended - you appear to be asking people to do your research for you. Stack Exchange is for specific questions. Google is for "what other options are available?" –  Norky Jan 3 '13 at 10:16

2 Answers 2

If by GFS you are referring to GFS2 (Global File System as sold by Red Hat, as well as being free), then multiple servers can write to it at the same time. Note that this belongs to a class of filesystems also called "global file systems", i.e. global filesystem is both a general concept and a specific implementation of that concept. More specifcally, GFS2 is a shared-disk filesystem

You have some kind of shared block storage device (FC, iSCSI, direct-attached with the right cabling topology) where two or more computers can directly 'see' a hard disk or thing-that-looks-like-a-hard-disk (block device). For multiple computers to be able to concurrently access a filesystem on that block device, you need some kind of global filesystem. GFS2 is one option, OCFS2 is another, as is Veritas Clustered Filesystem. Some kind of arbitration is needed to between servers to ensure they have a coherent view of the data, and do not try to write to the same areas (blocks) of the shared disk at the same time. In GFS2 this is done by Distributed Lock manager, and that relies on certain HA elements, i.e. the servers should be in an HA cluster together. The HA cluster pieces required for GFS2 are small. It might be possible to run without them, however only if you don't care about the integrity of your data.

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Thanks Khaled .

To use GFS2, cluster services needs to be running as you pointed out. If GFS2 is the file system resource in our cluster , then GFS2 will be mounted on only one host at the same time since it is a HA cluster. But our requirement is that GFS2 should be mounted on all the hosts at the same time . Looks like we will not be able to achieve this using GFS2. Is my understanding correct here ?

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