[Linux-cluster] multiple service instances with rgmanager

[Lon Hohberger]

On Tue, 2005-05-24 at 10:24 -0500, Jason Lanclos wrote:
> Is it possible setup a service that will run on 2 or more nodes at the same time?
> 
> I am testing RHEL4 and cluster/gfs for our mail server setup.
> Currently we have 2 RHAS 2.1 boxes attached to a SAN. All filesystems are ext3.
> One node handles all SMTP requests, and does virus scanning, mimedefang, spamassassin
> and several other things with the incoming mail.
> When its finished, messages gets handed off to the node that we have running the "mailstore"
> which has all the home directories, and handles all of the IMAP/POP connections.
> Needless to say, with everyone hitting the same server to receive mail, this machine
> can get pretty busy, while the sendmail node has plenty of processing power to spare.
> 
> So, I've pretty much replicated our setup using RHEL4 and cluster/gfs so both boxes can 
> receive mail, and service client connections for IMAP/POP.
> With the setup being this simple, I know I could not even worry about setting up services in
> rgmanager, but it would be nice to start/stop/check services on both nodes with one command.

Currently, no.  It's not really that difficult to add, and might be a
consideration for a future release.

However, you can have certain things be reused between services.  So,
you can have two services running the same set of initscripts.

Something like:

   <resources>
      <script name="a" path="/tmp/a"/>
      <script name="b" path="/tmp/b"/>
   </resources>
   <service name="foo1" domain="node1dom">
      <script ref="a"/>
      <script ref="b"/>
   </service>
   <service name="foo2" domain="node2dom">
      <script ref="a"/>
      <script ref="b"/>
   </service>

"clustat" will show you the state of those services with one command,
but to start/stop them, you'll have to use two commands.

(node1dom = restricted fd with only node1 in the list; node2dom = same,
for node2)

-- Lon