[Linux-HA] heartbeat with postgresql

[Greg Woods]

On Tue, 2010-10-19 at 10:01 -0600, Serge Dubrouski wrote:
> Any particular reason for using Heartbeat v1 instead of CRM/Pacemaker?

Um, maybe because heartbeat v1 has a much much much much less steep
learning curve? If you have a simple two-node cluster where one node is
just a hot spare, it is way way way way easier to get it working with
heartbeat v1.

The first time I ever set up a high availability cluster, going in
knowing nothing at all about it, I had a heartbeat v1 cluster working in
a couple of days. Already having had considerable heartbeat v1
experience, it took me a couple of months to get a cluster working under
heartbeat v3/Pacemaker. The pace of development is also high enough that
the documentation often lags behind reality. That is not a criticism, I
know how hard it is to keep the documentation up to date (I am already
in that mode now with these new clusters; nobody else knows how they
work so I can't even take a vacation now that I have some production
services running on them, until I finish writing up some administration
procedures).

Yes, no doubt a Pacemaker cluster is far more flexible, but when one
doesn't need all that flexibility and just wants a simple two-node HA
cluster, the simplicity of heartbeat v1 is very attractive.

This shouldn't be a big a mystery as it seems to be. Face up to it:
learning and properly configuring Pacemaker is HARD, even for
experienced sysadmins. And unless you need the additional flexibility
that Pacemaker offers, it seems like a lot of extra effort.

Will I use Pacemaker all the time in the future? Yes, because I have
already put in the effort to learn and configure it. Setting up a new
cluster, where I had an existing one to use as a template, took less
than a week. But that first time, it was difficult, time consuming, and
often frustrating. 

--Greg