[DRBD-user] DRBD primary/primary for KVM - what is the best option?

Bart Coninckx bart.coninckx at telenet.be
Wed May 12 19:10:57 CEST 2010

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


On Tuesday 11 May 2010 22:01:59 Florian Haas wrote:
> On 05/11/2010 08:56 PM, Ryan Manikowski wrote:
> >> Heartbeat normally takes care of both things: failing over and starting
> >> all resources at boot. I guess we need a Heartbeat resource agent that
> >> can use ietdadm. I really wonder what the webinar is about.
> >
> > No resource agent needed. Heartbeat automagically sources /etc/init.d
> > for daemon scripts. Just place inline as you would any other resource in
> > haresources and it will apply 'start/stop' according to status.
> 
> Sorry to put it this bluntly, but that's bogus. Firstly, it's not quite
> that simple, specifically for active/active setups. Secondly, no-one
> should be using haresources setup anymore, we have Pacemaker for a reason.
> 
> This might be insightful:
> http://www.linux-ha.org/doc/re-ra-iSCSITarget.html
> http://www.linux-ha.org/doc/re-ra-iSCSILogicalUnit.html
> 
> Cheers,
> Florian
> 

I've been looking into the code of these two Resource Agents and I came to the 
conclusion that they create, remove or migrate iSCSI targets and LUNs 
respectively. What I fail to see however is how they can be used to create an 
active/passive iSCSI cluster where a set of LUNs can be on an active DRBD 
resource on the first node and another set of LUNs can be on an active DRBD 
resource on the other node. Each node has its own iSCSI target software 
running, but is bound to its specific IP address I suppose. Moving the LUNs 
means moving them to another IET instance bound to another IP address, which 
is not really HA to the iSCSI initiators. 

What am I missing?

thx!


B.



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