[Systems] aslo cluster progress

[David Farning]

On Fri, Mar 12, 2010 at 9:40 PM, Bernie Innocenti <bernie at codewiz.org> wrote:
On Fri, 2010-03-12 at 12:48 -0600, David Farning wrote:
> Work this weekend will focus on setting up redundant 'masters' for the
> database, filesystem, and loadbalancer.

Will be traveling on Saturday, so I can assist only on Sunday.
The database part would be straight-forward if we would be content with
a master-slave configuration, but we probably want multi-master, right?

Yes, we require master-master.  The goal here is if one machine to go down, the other takes over.  Master-Master is the only arrangement in which the second machine can take over the writes.

As an FYI, as you predicted, database load is not going to be a problem for a _long_.  I think we can handle about 10 php servers with each database server.  Cache 1, memchached, has a hit rate in the mid 80%. Cache 2, the mysql cache, has a hit rate in the low 90%.  I just did a mysql dump and the size of the data base was just under 100MB 


>   The goal will be for a admin (human) to be able to manually switch
> control of the cluster from one node to the other.  From there it will
> be a matter of adding the High Availability (HA) function so the
> cluster can pass control around on its own.
>
> The interesting problem is not switching control from one machine to
> another machine.  The main problem is insuring that the orginal
> 'master' does not wake up and think that it is still in control.

The famous "split-mind" problem in clusters :-)


> After a couple of slow weeks learning puppet it is nice to be moving
> forward again.

For the record, I think it's ideal for managing the ASLO cluster and I'm
sorry that I still didn't get around to learn it properly.

Now that the basic plumbing is in place it will be pretty time effective for experienced admins like you and hhardy to review and improve the manifests.

david 
 --
   // Bernie Innocenti - http://codewiz.org/
 \X/  Sugar Labs       - http://sugarlabs.org/


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