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From:Mikael Ronström Date:September 14 2004 8:03am
Subject:Re: possible to bring up a subset of nodes?
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Hi Jim,
There is a bit of configuration "magic" around this case and also some 
partitioning logic.

First the 2 nodes when they try to perform a system restart they will 
not constitute a
majority and the partitioning service hasn't got all the bells and 
whistles yet during
system restart so there is a configuration parameter stating how long 
to wait until it
starts in a partitioned state
StartPartitionedTimeout which by default is 60 seconds (= 60000 
milliseconds)

In addition there is another configuration parameter that ensures that 
as often as
possible a full cluster is restarted. This sets the time that the 
cluster waits for processes
to join before starting the system restart.
StartPartialTimeout which by default is set to 30 seconds.

So by default no system restarts are initiated until 30 seconds have 
passed after
starting the DB nodes and if in partitioned state one waits for 60 
seconds before
attempting the system restart.

Rgrds Mikael

2004-09-14 kl. 01.49 skrev Jim Hoadley:

> Using a 4-node cluster with 2 replicas, my testing has shown that a 
> running
> cluster will continue to run with a subset of DB nodes, as long as all 
> data is
> present. This is as expected :)
>
> But testing also show it is not possible to bring up just a subset of 
> nodes.
>
> In practice, this means that if I'm lucky enough to have the "right" 2 
> nodes
> crash in a 4-node cluster, I'd best not shut them down for even a few 
> seconds,
> for if I do the cluster won't be able to restart until all 4 nodes can 
> be
> brought back online.
>
> Is this observation accurate? Comments?
>
> -- Jim
>
>
>
> 		
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Mikael Ronström, Senior Software Architect
MySQL AB, www.mysql.com

Clustering:
http://www.infoworld.com/article/04/04/14/HNmysqlcluster_1.html

http://www.eweek.com/article2/0,1759,1567546,00.asp


Thread
possible to bring up a subset of nodes?Jim Hoadley14 Sep
  • Re: possible to bring up a subset of nodes?Mikael Ronström14 Sep