The question I have, are you trying to actually load balance things? Or just
have a remote location that you can fire up with live data at a moments
notice? Basically, are you wanting an active/active configuration, or
active/passive?
active/active across DC's can get kind of hairy depending on what the
network looks like. active/passive won't give you any performance gains,
but can simplify the configuration, while providing the HA you seem to be
after. As Kaia pointed out, what the traffic looks like (reads vs writes)
is a consideration. If it is something that users don't write to, and data
doesn't have to be replicated across DCs frequently, this further simplifies
things.
Ultimately, the configuration will depend on what the application and
network looks like currently, and what level of redundancy you want / need.
-- Dan.
On Wed, May 19, 2010 at 1:40 PM, Matt Iavarone <
matt.iavarone@gmail.com>wrote:
> I think the original question was around stateless load balancing, not
> clustering. Cross DC clustering is a headache, but HA web sites aren't
> exactly terchnical challenges these days.
>
> On May 19, 2010 4:33 PM, "Alex Dean" <alex@crackpot.org> wrote:
>
>
> On May 19, 2010, at 2:47 PM, keith smith wrote:
>
> >
> >
> > Hi Plug,
> >
> > I am considering combining the ...
>
> You're entering a world of pain. :)
>
> HA is cool, but is no panacea. If you haven't actually experienced
> downtime due to your server crashing or your datacenter losing connectivity,
> I recommend thinking long and hard about it. Don't solve a problem you
> don't have. The downtime created from unneeded failovers will likely exceed
> the actual/real downtime caused by either a server or datacenter being
> offline. Managing the cluster itself (as distinct from the services
> provided by the cluster) needs to be accounted for as an
> expense/responsibility.
>
> I don't want to sound overly pessimistic. I've set up quite a few HA
> clusters, and actually enjoy it most of the time. But it WILL cause you
> headaches in the middle of the night which you wouldn't have had if you only
> had a single server.
>
> Leave yourself lots of time to set up a development/test cluster, and abuse
> it in many ways. Pull out network cables, kill the switch, yank out power
> cables, etc. Do this with real hardware, not VMs.
>
> When the cluster nodes lose contact with each other, both will decide to
> become primary. This is a split brain. This can happen when the switch
> in-between them gets busy and starts dropping pings. Now, you can always
> recover from such things. I'm just recommending you become very familiar
> with these issues before going live with this setup.
>
> http://clusterlabs.org/wiki/Main_Page
> http://people.linbit.com/~florian/heartbeat-users-guide/
>
> Let me/us know if you have specific questions once you start setting things
> up. Good luck!
>
> alex
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