Re: Passive node in a cluster ?

JF Mezei wrote:
> Just an idea:

And a bad one at that...

> It would be nice to have a node in a cluster which would NOT freeze upon
> loss of quorum. (consider a node that monitors the cluster, disk space,
> who has what disks mounted in the cluster etc).
>
> If that node had 0 votes, its own system disk, and would only mount
> cluster disks in a read only mode, could this cause problems in cases of
> cluster partitioning ?

Of course it could. If the cluster partitions, you could be reading
old data off the cluster disks. You could be making very bad decisions
based on garbage data. You could be attempting to master locks that
another node has already mastered.

> Why am I bringing this up ? I was using one node's serial port to
> monitor the OPA0: of another node.

Hence we always have cluster console systems outside of the cluster.

> (yes, I know, make that node outside of the cluster, but there are
> advantages to being inside the cluster in terms of cluster management etc).

But far more disadvantages than advantages. There is cluster monitoring
and there is cluster management. The two aren't the same. Manage the
cluster from one system but monitor it from another.

The simplest approach is to use a quorum disk that gives you the
deciding vote and give your monitoring node 0 votes. Alternatively,
give yourself a vote and then you and one of the production nodes could
be up and you'd still have quorum. You'd only lose quorum if you lost
both production nodes in which case you're dead anyway.

.../Ed

.

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