Loon(y) Juice

Remus-fu with DRBD, GFS2 & Redhat Cluster on Debian

Refer to http://www.loonjuice.com/2010/06/06/remus-fu to get Debian & Xen with Remus installed, configured & running.

Then, change the disk of the VM to use an image location being on a GFS2 mounted, DRBD distributed, clustered file system! (eg used below is /usr/gfs0 )

Current Xen 4.1-unstable includes Remus & uses/patches the 2.6.31.13 Linux kernel.

Build & install the latest DRBD sources, from http://www.drbd.org/docs/install/

ie:

download the relevant drbd-*.tar.gz, extract to /usr/local/src

run ./configure –with-km; make KDIR=/lib/modules/2.6.31.13/build ; make KDIR=/lib/modules/2.6.31.13/build install

You then need to configure DRBD using the same /usr/local/etc/drbd.conf on both hosts, eg: using /dev/loop0 as the backing disk device!!

global {
minor-count 10;
}

resource drbdr1 {
protocol C;
meta-disk    internal;
device        /dev/drbd0;
##disk        /dev/mapper/VG-LV_name;
disk        /dev/loop0;

startup {
wfc-timeout 30;
degr-wfc-timeout 30;
become-primary-on both;
}

disk {
on-io-error detach;
}

syncer {
rate 90M; # Note: ‘M’ is MegaBytes, not MegaBits
}

net {
allow-two-primaries;
after-sb-0pri discard-younger-primary;
after-sb-1pri discard-secondary;
after-sb-2pri call-pri-lost-after-sb;
}

on remus1 {
##device        /dev/drbd0;
##disk        /dev/loop0;
##disk        /dev/mapper/VG-LV_name;
address        192.168.X.Y1:7789;
##meta-disk    internal;
}

on remus2 {
##device        /dev/drbd0;
##disk        /dev/mapper/VG-LV_name;
address        192.168.X.Z:7789;
##meta-disk    internal;
}

}

Ensure that the same entries for hosts ‘remus1′ & ‘remus2′ are in each hosts /etc/hosts file! (V.IMPORTANT)

Now instantiate/initially-start DRBD with the following command set:

drbdadm create-md drbdr1

drbdadm attach drbdr1

drbdadm connect drbdr1

watch cat /proc/drbd

Then finally set Dual Primary mode with: (as long as you have dual-primary enabled in your active drbd.conf as perhttp://www.drbd.org/users-guide-emb/s-enable-dual-primary.html )

drbdadm primary drbdr1

With both hosts running in DRBD Primary modes (cat /proc/drbd |grep “Primary/Primary”) you can now get the GFS2 filesystem built on /dev/drbd0

mkfs.gfs2 -t clusternamefromcluster.conf:gfs1 -p lock_dlm -j 2 /dev/drbd0

Then you can mount the GFS2 filesystem on each host:

mkdir /usr/gfs0

mount /dev/drbd0 /usr/gfs0

(on each host)

Check status of Cluster, GFS & DRBD:

cat /proc/drbd

cman_tool status

cman_tool nodes

gfs2_tool df

More to be added, but you can install & run up a domU as per the original Remus-fu post using an image on /usr/gfs0 !