[Linux-cluster] Can i use 2 nodes from a cluster?
misch at schwartzkopff.org
Tue Oct 22 20:46:28 UTC 2013
Am Dienstag, 22. Oktober 2013, 22:21:02 schrieb C. Handel:
> place a loadbalancer in front of the cluster. Buy hardware, for example F5
> or coyote. Or go for software with haproxy and keepalived.
Use ldirectord and pacemaker. Trust me.
> The software
> loadbalancer is a shared nothing. You only need to keep the config in sync
> (for example using csync2). Configure load balancing with sticky sessions
> based on incoming ips.
You might want to sync the stored connections. ipvs has a demon, that takes
care of this.
> Create a redhat cluster with four nodes. Main service provided by rhcs is
> GFS2. This allows you to share configfiles and web delivery files the same
> on all nodes.
Not needed to set up a full blown RH cluster. Keep the config files in sync
with a simple rsync or csync. No further shared storage needed. Just use
corosync for the cluster communication and pacemaker for the resource
management. Resources are the ldirectord and the virtual IP.
> Start an apache on each node (via clones).
Or start it separate on every node via init or systenmd. no cluster needed in
the backend web servers.
> Traffic goes through loadbalancer and hits all rhcs nodes. Bandwith limit
> is the interface of the loadbalancer. Processing limit is from each
> RHCS-node. Disk I/O limit is from the SAN backing the GFS2 in combination
> with the GFS2 (reading should be no issue, heavy writing will trash the
> cluster via locks)
Please think twice of you really need a cluster on the backend web servers. In
most of the designs you can live without. Which makes live much easier.
Dr. Michael Schwartzkopff
Tel: (0162) 1650044
Fax: (089) 620 304 13
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