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Re: [Linux-cluster] delete node



Scott McClanahan wrote:
> On Tue, 2007-04-10 at 13:54 +0100, Patrick Caulfield wrote:
>> Scott McClanahan wrote:
>>> On Tue, 2007-04-10 at 03:37 -0400, Patrick Caulfield wrote:
>>>> Scott McClanahan wrote:
>>>>> Hello, we are running CentOS 4.3 and the latest cluster suite
>>>> packages
>>>>> from the csgfs yum repository for this release and need to delete a
>>>>> cluster member.  According to the documentation we need to restart
>>>> all
>>>>> cluster related services on all remaining nodes in the cluster after
>>>> the
>>>>> node has been removed.  This is a four node cluster so removing one
>>>> node
>>>>> obviously degrades the cluster to three nodes, but we can have the
>>>>> remaining cluster members recalculate the number of votes to remain
>>>>> quorate.  It still surprises me that we have to bring down the
>>>> entire
>>>>> cluster just because we are deleting a node.  Any feedback as to why
>>>>> this might be?
>>>>>
>>>> You only need to reboot the whole cluster if you want to remove all
>>>> trace of the
>>>> node from /proc/cluster/nodes. If you're not bothered about that them
>>>> just
>>>> remove with "cman_tool leave remove" and forget about it.
>>>>
>>>> --
>>>> Patrick
>>>>
>>>> Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod
>>>> Street,
>>>> Windsor, Berkshire, SL4 ITE, UK.
>>>> Registered in England and Wales under Company Registration No. 3798903
>>>>
>>>> --
>>>> Linux-cluster mailing list
>>>> Linux-cluster redhat com
>>>> https://www.redhat.com/mailman/listinfo/linux-cluster
>>>>
>>> Ok, thanks for the answer.  To further elaborate my concern, if I want
>>> to rebuild an existing cluster member and reintroduce it to the cluster
>>> how do you suspect the cluster would handle that.  What would be the
>>> best way to rebuild an existing cluster member.  Other than the traces
>>> of node details in /proc/cluster/nodes is there any kind of state kept
>>> locally on these cluster nodes that would cause issues if I rebuild the
>>> node and attempt to transparently add it back to the cluster.
>>>
>>> Would I need to delete the cluster member from the cluster config using
>>> the proper utilities and then add it again?
>>>
>>> Could I avoid having to delete the cluster member at all from the
>>> cluster and simply rebuild/reintroduce?
>> If the rebuilt node has the same node name and IP address (and cluster sofware,
>> obviously) then there will be no problems. The other members of the cluster will
>> welcome it with open arms as an old friend.
>>
>> If you give it a different name/ip address then it will appear in the cluster as
>> a new node and its old incarnation will remain in the list as 'dead'.
>>
>>> Why?  :)
>> All the existing members care about the old node is that it has the same name,
>> IP address and node ID. Anything else is nothing to do with them really, or can
>> be sorted out at run time.
>>
> Sorry to be so chatty but just to be sure (this is production), I can
> just rebuild the node without deleting it from the config?  I will
> obviously need to copy the cluster.conf file to the newly built node but
> I thought that the node ID was "assigned" during the joining process of
> cluster membership.  If that is the case and as long as I don't manually
> override the node ID, do I really have to worry about anything other
> than the hostname/IP?  Not sure if it helps to reiterate that this is
> the cluster suite software built for RHEL version 4.3.

Sounds like it'll be fine. Yes, the nodeid is normally assigned by cman (you can
override it but few people seem to). So if the node joins with the same name/IP
address it will get its old node ID back. As far as cman is concerned it will be
the same node as it always was.

-- 
Patrick

Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street,
Windsor, Berkshire, SL4 ITE, UK.
Registered in England and Wales under Company Registration No. 3798903


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