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Re: Xsan + NFS + grid engine


One other thing you should carefully look at is which network is being
used for NFS traffic and which is being used for the Xsan meta data.
If
they're both on the same network, as the NFS load increases you'll lose
connections from the NFS servers to the Xsan MDC. This will cause a
fail over and other problems.

Xsan MDC traffic is on a different network which is just for the three portal machines along with an uplink to the rest of the WAN. NFS mounts are all on a private cluster network.

The other thing to look at is how the files are being accessed.
Picture
this:
	nfs client 1 using nfs server A
	nfs client 2 using nfs server B
If nfs client 1 and nfs client 2 access the same file with one of them
writing, you most definitely will lower performance.  All nfs clients
that are accessing the same files should all go through the same nfs
server.

My earlier comments about "all Xsan machines crashing" outweighing "performance" apply here as well.

I'm confused now:  The reasons we built this setup were to:

* lower the client:server ratio on NFS (increasing reliability)
* be able to scale I/O by adding portal san machines as needed.

Reading into your comment, it sounds like this isn't the way you would set up such a system. Do you have a better architecture than re-sharing this way?

An update: I was able to increase stability by splitting up the stderr and stdout streams from my various jobs and lowering contention on any single file. The portal machines still crash if I load the cluster heavily, but it seems to have to do with file contention while there are a large number of writes going on.

Assuming that my goal is to build a stable, scalable san for use in cluster computing (all the nodes pointing at a common pool of data), is there a better way to do it than this NFS re-sharing?

-Chris Dwan _______________________________________________
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References: 
 >RE: Xsan + NFS + grid engine (From: Glenn Heinle <email@hidden>)



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