On Thu, Jan 26, 2006 at 05:53:41PM -0600, Jim C. Nasby wrote:
> On Mon, Jan 23, 2006 at 12:59:55PM -0500, Andrew Sullivan wrote:
> > There's no system commercial available, AFAIK, that can offer that

> What I was replying to in
> http://gborg.postgresql.org/pipermail/slony1-general/2006-January/003678.html
> seems to indicate otherwise, but maybe I was reading it wrong...

Some systems can replicate _parts_ of the data in real time.  For
instance, they can ship logs of transactions; and in the case of the
bank, you're willing to wait anyway, if you're getting your cash.  In
the case of, for instance, online trading, there's actually a
settlement period involved, so if the transaction were lost by
someone because of a data systems disaster, they'd just invoke the
_force majeure_ clause and walk away.  There'd be some damages, but
that's what risk management actuaries are employed by banks to
mitigate.  It's really a matter of trade-off. 

> What I do know is that every sales call I've been on someone at some
> point has asked about PostgreSQL 'clustering' for HA, so there's
> definately a lot of interest in HA out there (thought granted most of
> these folks wouldn't spring for WAN HA...)

Sell them hardware failover.  That's what IBM would sell you if you
were using DB2: two machines running (in an example I'm familiar
with) HACMP, and one can take over from the other in the case of
failure.  You can do this with Linux and others too.  If it's only HA
and not workload scale you want from a cluster, you can have it
today.  IBM won't guarantee 5-nines on these arrangements, but I
understand that they _will_ offer such guarantees on Linux-on-390, so
you still have an (admittedly expensive) option if you want it badly
enough.

A

-- 
Andrew Sullivan  | ajs at crankycanuck.ca
A certain description of men are for getting out of debt, yet are
against all taxes for raising money to pay it off.
		--Alexander Hamilton