From: Fabio M. Di Nitto <fdinitto redhat com>
To: linux-cluster redhat com
Sent: Tuesday, July 3, 2012 7:04 AM
Subject: Re: [Linux-cluster] CLVM in a 3-node cluster
On 07/02/2012 11:39 PM, urgrue wrote:
> On 2/7/12 19:14, Digimer wrote:
>> On 07/02/2012 01:08 PM, urgrue wrote:
>>> I'm trying to set up a 3-node cluster with clvm. Problem is, one node
>>> can't access the storage, and I'm getting:
>>> Error locking on node node3: Volume group for uuid not found: <snip>
>>> whenever I try to activate the LVs on one of the working nodes.
>>> This can't be "by design", can it?
>> Does pvscan show the right device? Are all nodes in the cluster? What
>> does 'cman_tool status' and 'dlm_tool ls' show?
> Sorry, I realize now I was misleading, let me clarify:
> The third node cannot access the storage, this is by design. I have
> three datacenters but only two have access to the active storage. The
> third datacenter only has an async copy, and will only
> (manually) in case of a massive disaster (failure of both the other
> So I deliberately have a failover domain with only node1 and node2.
> node3's function is to provide quorum, but also be able to be activated
> (manually is fine) in case of a massive disaster.
> In other words node3 is part of the cluster, but it can't see the
> storage during normal operation.
> Looking at it another way, it's kind of as if we had a 3-node cluster
> where one node had an HBA failure but is otherwise working. Surely node1
> and node2 should be able to continue running the services?
> So my question is, do I have an error somehwere, or is clvm really
> actually not able to function without all nodes being active and able to
> access storage?
CLVM requires a consistent view of the storage from all nodes in the
cluster. This is by design.
failure during operations (aka you start with all nodes able
to access the storage and then downgrade) is handle correctly.
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