[Linux-cluster] Starter Cluster / GFS

Nicolas Ross rossnick-lists at cybercat.ca
Wed Nov 10 12:07:33 UTC 2010


> If you want the FS mounted on all nodes at the same time then all those 
> nodes must be a part of the cluster, and they have to be quorate (majority 
> of nodes have to be up). You don't need a quorum block device, but it can 
> be useful when you have only 2 nodes.

At term, I will have 7 to 10 nodes, but 2 at first for initial setup and 
testing. Ok, so if I have a 3 nodes cluster for exemple, I need at least 2 
nodes for the cluster, and thus the gfs, to be up ? I cannot have a running 
gfs with only one node ?

> If you are only ever going to have the SAN volume mounted on one device at 
> a time, don't bother with GFS and make the SAN block device a fail-over 
> resource so that only one node can mount it at a time, and put a normal 
> non-shared FS on it. You will get better performance.

I do need a shared file-system, I am aware of the added latency, we 
currently have some latency on our xSan setup. But we do also need on some 
services an additional block-device that is accessed only by one node and is 
indeed failed-over another node when a node fail.

> The number of journals needs to be equal to or greater than the number of 
> nodes you have in a cluster. e.g. if you have 5 nodes in a cluster, you 
> need at least 5 journals. If you think you might upgrade your cluster to 
> 10 nodes at some point in the future, then create 10 journals, as this 
> needs to be done at FS creation time.

That I got. It's the size that I don't know how to figure out. Will 32 megs 
will be enough ? 64 ? 128 ?


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