[Sunhelp] mirroring/clustering/failover

[James Lockwood]

On Fri, 12 May 2000 beemern at telecom.ksu.edu wrote:

> we have two Enterprise 150's that do web serving/dns/etc
> 
> we are wanting to to configure so that each machine is identical to the
> other (real-time mirroring) and also "load-balancing" so that they are
> both 'hot' and can serve requests
> 
> any suggestions on how and what to use??

A couple of big questions:

Is your content static or dynamic?
If dynamic, is it read-only, read-mostly or read-write to some sort of DB?
If r/w, how closely do they need to be in sync?
Do you want user requests to arbitrarily choose a server each time, or
should a user session be bound to a single server (deja.com is a good
example of this)?
Are updates to content regularly pushed out by a back end system, or is
the live data directly modified?

Depending on your needs and software you may need anything from a perl
script or two to an expensive HA package.  The bottom line is that while
DNS and HTTP are trivial to parallelize, services behind them (such as
databases) usually are not.

-James