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Re: Best way to setup a cheap web cluster?

Am Mit, 2003-10-08 um 15.43 schrieb Ryan Nowakowski:
> Hey folks,
> I'm trying to setup a cheap debian web cluster using tools from the
> linux-ha project.  We're using heartbeat and mon to monitor services
> and do the failover.  We'd like to setup shared disk space without
> buying any new hardware.  We have three cheap servers in the cluster.
> We're thinking about using drbd for the shared disk space.

As you already said: Use drbd for the shared storage and heartbeat as a
cluster manager. That way you'll get an easy to setup failover-cluster
completely based on OSS and without any "special" hardware.

BUT this is not a load-balanced cluster, only one machine will handle
the load, it won't be spread about both machines. DRBD currently cannot
run in active-active (i.e. most filesystems can't and the GFS support is
not yet ready). You'll have two machines, one handles the requests - if
this machine fails, the second one will take over and resume processing
incoming requests, but until then it sits there and does nothing (well,
monitoring the primary node - but that doesn't count).

Speaking of "web-clusters" you probably mean a load-balanced HTTP
cluster (with HA features). You'll need some sort of loadbalancer (see
one of the recent threads about cluster and balancers). Neither DRBD
(shared storage) nor heartbeat (cluster-manager) will do this for you.
Instead you could use LVS (www.linuxvirtualserver.org)

> How have others setup web clusters using debian?  We're not adverse to
> backporting packages or using outside apt sources if necessary.

Either way, you don't need any backports - almost (?) everything should
be packaged for Debian. If you want the latest versions you'll have to
compile some sources by yourself though.

best regards,
Markus Oswald <moswald@iirc.at>  \ Unix and Network Administration
Graz, AUSTRIA                     \ High Availability / Cluster
Mobile: +43 676 6485415            \ System Consulting
Fax:    +43 316 428896              \ Web Development

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