[Linux-cluster] Building SAN with Red Hat Cluster. Is it possible?

[Benjamin Marzinski]

On Tue, Dec 12, 2006 at 12:10:28AM +0300, Igor Zhbanov wrote:
> Hello!
> 
> I want to build system consisting of several frontend-nodes and two-four
> backend (storage) nodes. I don't want to use hardware shared storage for
> some reasons. So, we can use some networking block device to connect two
> nodes (e.g. DRBD v0.8 in primary/primary mode, or GNBD?) if needed.
> The question, is it possible to setup Red Hat Cluster in such configuration:
> 1) over DRBD or local hard drives if possible on two or four storage nodes;
> 2) to be able mount file system at frontend nodes which have no direct 
> access
>   to shared storage device, i.g. is it possible to mount file system over
>   network?;
> 3) to have failover and load-balancing storage nodes, so each node will hold
>   entire copy of stored data, so storage nodes can be accessed in parallel
>   and if one node goes down, system will function correctly.
> 4) If it is possible to mount file system on some other node, will it be
>   mounted as file system or firstly some block device will be exported
>   to that node and file system will be mounted over it?
> 
> Thank you.

The short answer is, well... sort of.

If you want to have several frontend nodes talking to 2 backend GFS nodes via
NFS, then I believe that the answer is yes. I haven't tried it myself, but
people claim to have run GFS on top of primary/primary DRBD. However, I think
DRBD limits you to 2 nodes.

The other way to do this involves cluster-mirror, which hasn't been officially
released  yet. This will allow you to have any number of backend nodes running
GNBD. The exported GNBD devices will all be bundled into a mirror device on the
frontend nodes, which would run GFS. The cluster mirror code is available via
CVS, if you want to try this setup out.

-Ben

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