[Linux-cluster] < cluster.conf problem >

[Jonathan E Brassow]

Quorum is a number of machines greater than or equal to (n/2 +1) of the 
total cluster machines.
There is no way for two groups of machines in a cluster to have 
"quorum".  Only one group (which may be all the machines) can have this 
status.

When a group of machines has quorum, they can perform cluster 
operations.  The idea of quorum prevents "split-brain" or two separate 
groups of machines from thinking they are in control of the cluster - 
and thus potentially corrupting resources because they do not 
acknowledge the existence of the other group.  (Think multiple writer 
problem.)

You should reboot all your machines at the same time.  (Or at least do 
cman_tool join on all the machines at close to the same time.)  This 
allows the machines to form a quorate group and start performing 
cluster operations - like starting and performing fencing.

  brassow

P.S. Manual fencing sucks for anything more than simple evaluation.  My 
guess is that you will encounter more problems/questions because of 
manual fencing.

On Apr 19, 2006, at 9:28 AM, Pool Lee, Mr <14117614 at sun.ac.za> wrote:

> Hi…
>  
> I did that, thanks.
>  
> Now I have trouble getting fence_tool join to work. I did cman_tool 
> join and I’m able to see the nodes under /proc/cluster/nodes…
>  
> But fence seems to wait for something called  “quorum”..
> In the cluster.conf file just said fence manually…
>  
> What would be the problem?
>  
> Lee
>  
>
> He who has a why to live can bear with almost any how.
> Friedrich Nietzsche
>
> From: linux-cluster-bounces at redhat.com 
> [mailto:linux-cluster-bounces at redhat.com] On Behalf Of Jonathan E 
> Brassow
> Sent: 19 April 2006 04:14 PM
> To: linux clustering
> Subject: Re: [Linux-cluster] < cluster.conf problem >
>  
> Have you started the CCS daemon (ccsd)? The init script should start 
> this on bootup. You really just need to create the cluster.conf file 
> (by hand or by GUI) and copy it to all your nodes. Then reboot.
>  
> brassow
>
>  
> On Apr 18, 2006, at 3:14 PM, Pool Lee, Mr <14117614 at sun.ac.za> wrote:
>>  
>> Hi…
>>  
>> I have 5 nodes and 1 head node. I want to setup gfs so that I can 
>> bunch together the 5 nodes, each have lvm’s.
>>  
>> I’m having trouble setting up cluster.conf. I follow the manuals 
>> example for gfs, not gfs2, and it says that it cant connect to css.
>>  
>> I’m running FC5 on all my machines.
>>  
>> Lee
>>  
>>  
>> He who has a why to live can bear with almost any how.
>> Friedrich Nietzsche 
>>  
>> <image001.gif>--
>> Linux-cluster mailing list
>> Linux-cluster at redhat.com
>> https://www.redhat.com/mailman/listinfo/linux-cluster
> --
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