[DRBD-user] Re: Just making sure DRBD is the right project for me... ; -)

[Helmut Wollmersdorfer]

Evert Meulie wrote:
 > http://linux-vserver.org/Vserver+DRBD looks promising, since 90% of
 > the changes will be made in the vservers on the node

IMHO the synchronization alone is not a reason for using vserver or XEN.
Virtualization techniques also have some disadvantages like more complex 
network configuration.

If there would not be a need to consolidate a server (with root access 
by a foreign person) into my cluster, I would be happy with rsyncing 
/etc, syncing the packages with the Debian style [get|set]-selections, 
and using DRBD for service related data files.

> Would it also work to mount the DRBD device as /var/lib/vservers, 
> instead of /var/lib/vservers/<vserver-name> , and hereby take all 
> vservers in 1 go?

Yes, mirroring /var/lib/vservers was my first test configuration.

But keep in mind, that in such a case _all_ vservers will failover (and 
'boot' more or less slowly). This means, that a crash of a single 
vserver causes unnecessary failovers of the other vservers.

Also I only have test experience with such a configuration.

Here is my /etc/ha.d/resource.d/vserver script:
----snip----
#!/bin/bash
#
# This script is intended to be used as resource script by heartbeat
#
# Jan 2005 by Helmut Wollmersdorfer.
#
###

VSERVER="/usr/sbin/vserver"

RES="$1"
CMD="$2"

case "$CMD" in
     start)
     	$VSERVER $RES start
	;;
     stop)
     	# exec, so the exit code propagates
	exec $VSERVER $RES stop
	;;
     status)
         $VSERVER $RES status | grep running > /dev/null
	if [ $? -eq 0 ]
	then
	    echo "running"
	else
	    echo "stopped"
         fi
	;;
     *)
	echo "Usage: vserver VSERVER-NAME {start|stop|status}"
	exit 1
	;;
esac

exit 0
----snap----

Helmut Wollmersdorfer