Serge Dubrouski wrote:
> This one is much better:
> http://www.clusterlabs.org/mediawiki/images/f/fb/Configuration_Explained.pdf

Thanks! That's greatly appreciated.

>>>> - resource supporting active-active configuration; do you mean like
>>>> Apache instances in 2 resource groups configured to use different IP
>>>> addresses so they would not conflict?
>>> I mean that Apache should have a shared filesystem underneath it or
>>> some kind of another mechanism that will make sure that both instances
>>> have the same content. Also if you try to make an active-active
>>> filesystem you have to make sure that it support concurrent access on
>>> different nodes, i.e. you have to use something like OCFS2 or so.
>> Hmm I was thinking rather of 2 different iSCSI targets or NDB devices, 1
>> for each resource group -- is switching them possible on failover /
>> failback?
> 
> Then it's not active/active is it?

I'm sorry? Perhaps I imagine it in a wrong way, but suppose node 1 has 
resource group, say, apache_a on iSCSI target A, and node 2 has resource 
group apache_b on iSCSI target B.

Now, both are running their res. groups simultaneously (hence I think of 
them as active/active), and on the node 1 failing, node 2 mounts iSCSI 
target B and starts rg apache_b. And vice versa.

Is that not active/active?

More importantly, is such configuration achievable using 
Heartbeat/Pacemaker and CRM (cause that's the holy grail I'm trying to 
build)?

> OCFS2 can be used for shared filesystem and as far as I know Oracle
> recommends it for using even in Oracle RAC, MySQL is a different thing
> though. I don't know how to build an active/active MySQL cluster and
> I'm pretty sure that it requires more that a shared FS, the database
> itself should support concurrent access from different nodes to its
> data.

Thanks!

Regards,
mk

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