cyrus replication : master to replica and replica to master

[Carson Gaspar]

On 10/23/09 7:42 AM, David Carter wrote:
> On Fri, 23 Oct 2009, Bron Gondwana wrote:
>
>> I've seen heartbeat get split brain before.  We gave up on it.  We do
>> all our fencing via humans now!  Check the KVM, kick the box, manually
>> run the failover script.
>
> Some of my colleagues have had a lot of grief with Heartbeat going split
> brain. It seems to really be designed for a pair of machines sitting next
> to each other in a rack with a serial link for the heartbeat, rather
> servers installed in a pair of machine rooms three miles apart.

To be fair to heartbeat, if you're getting unexpected split brain, then you have 
configured it incorrectly. A 2 node cluster without _extremely_ reliable 
communication and fencing between the nodes requires a tie-breaker service. This 
is true of any clustering technology I have ever seen. Heartbeat provides a 
light-weight quorum service for just this purpose.

Of course if you only have 2 sites, and the site with the "extra" vote goes 
down, you lose the service. Anything else requires 3 sites, or a "meatware" 
failover decision.

-- 
Carson