[Linux-cluster] replication

[David Siroky]

Hi!

I'm new to clustering. I'm planning to build at least 3-node
fault-tolerant cluster as a web server (based on Ubuntu distribution). I
want all nodes to be symmetric from user view. I don't want to replicate
the system itself but only data for webpages. Each node will have e.g. 2
partitions - 1 for system and 1 for shared data. 
First I thought the GFS might be the right solution for me but then I
realized it is suited for environments with dedicated storage servers or
SANs and clients using those data via GNDB (in other words data is
separated from clients).
I want each node to have its own replica and I don't want to use tools
like unison or FAM/IMON. That's an asymmetric replication. Is there any
solution for this like some simple "network raid1" using GFS or anything else?
Maybe exporting their paritions over GNDB and then joining them with SW
RAID1 should solve this but it seems to me as a nonelegant solution
(complicated administration of extending the cluster, too many layers -
GNDB-RAID-GFS).

Can anyone show me the right direction?

Thank you.

David