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how to add a new cluster node to a cluster with i/o fencing

Created: 25 Apr 2013 | 8 comments

strangely i have not been able to find the procedure adding a cluster node to a cluster with I/O fencing. can had be running while adding a new node? i know without I/O fencing it is perfectly easy to do. 

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arangari's picture

I think the 'installvcs -addnode' handles the fencing  scenario too. Did you try that?

Thanks and Warm Regards,

Amit Rangari

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mikebounds's picture

Fencing makes little difference when adding a node and there is no need to stop "had" on other nodes.  Only differences for fencing are those that are local to node been added (i.e new node needs to be able to see fencing coordinator diskgroup and needs fencing files set-up (look at /etc/*fen* on other nodes)

Mike

UK Symantec Consultant in VCS, GCO, SF, VVR, VxAT on Solaris, AIX, HP-ux, Linux & Windows

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IdaWong's picture

on the new node, gabconfig -a doesn't show any seed

lltstat -nvv looks fine.

existing nodes' llt gab were untouched. only the new node's llt and gab were restarted

what might be the problem?

this is 5.1sp1rp3

any idea?

mikebounds's picture

Have a look at /etc/llttab on all the nodes - if there is an exclude line, then this will limit the nodes they can see so you will need to change or remove the exclude line and restart LLT.  If there is no exclude line and you have started llt and gab on the new node and gabconfig -a shows no seeding on new node, then this suggests the heartbeat links are not physically connected.

If you are still having issues please post from each node (existing and new)

/etc/llttab
/etc/llthosts
output from lltstat -nvv
output from gabconfig -a
 

Mike

UK Symantec Consultant in VCS, GCO, SF, VVR, VxAT on Solaris, AIX, HP-ux, Linux & Windows

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stinsong's picture

Hi Ida,

I think maybe you missed the steps to modify /etc/llttab on the new node to have the same cluster id(the number after set-cluster) and different node id in /etc/llthosts with existing nodes of the cluster.

And you need to modify /etc/gabtab on the existing nodes to make the right number of seeding after the character "/sbin/gabconfig -c -n". The number X after -n option is the number of nodes in the cluster. so you need to add 1 if there is one node add in the cluster.

IdaWong's picture

hi stinsong,

unfortunately, that is not it. cluster IDs are the same in /etc/llttab files.

Gaurav Sangamnerkar's picture

Hi Ida,

on the 2 running nodes, whats the config in gabtab file ?  if the gab is seeded on existing cluster with 2 nodes, it won't accept the 3rd node even though the config files are correct  & gab is module loaded in the kernel so I would assume the kernel of the 2 nodes only would take 2 seeds of gab.

on the new node if you have kept gabtab to n3, that means that node is waiting for 3 nodes to be available & it won't detect the other 2 gab seed because of unique membership ID of the gab (you can observe this in gabconfig -a output)

I am sure offline method would solve this. You can keep your apps running by force stopping "had", stopping fencing, unload fencing module, stop gab , unloading gab module , modify gabtab file for 3 nodes, reload gab, reload fencing & restart had.

G

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arangari's picture

AFAIR, gabconfig -n2 would mean atleast 2 nodes are needed for seeding. new nodes can join. i think even the gabtab entry in new node may not matter - as the GAB is already seeded for given cluster-id. 

could you provide the llttab, llthosts, gabtab on all the nodes, as output of gabconfig -a, and lltstat -n from all the nodes. 

Thanks and Warm Regards,

Amit Rangari

If this post helped you resolving the issue, please mark it as solution. _____________________________________________________________________________