We have installed 3 nodes drbd, but it is not reliable as two DRBD server setup. We are facing some issues after the installation.

[root@drbd1 ~]# yum install drbd83 kmod-drbd83  
[root@drbd2 ~]# yum install drbd83 kmod-drb83  
[root@drbd3 ~]# yum install drbd83 kmod-drb83

Insert the lines(for first 2 nodes )

vi /etc/drbd.conf

global { usage-count yes; }  
common { syncer { rate 10M; } }  
resource r0 {  
protocol C;  
net {  
}  
on drbd1.isb.ots.com {  
device    /dev/drbd0;  
disk      /dev/hda5;  
address   192.168.1.224:7789;  
flexible-meta-disk  internal;  
}  
on drbd2.isb.ots.com {  
device    /dev/drbd0;  
disk      /dev/hda5;  
address   192.168.1.223:7789;  
flexible-meta-disk  internal;  
}  

[root@drbd1 ~]# modprobe drbd  
  
[root@drbd2 ~]# modprobe drbd  
  
[root@drbd2 ~]# vi /etc/ha.d/haresources  
  
[root@drbd1 ~]# drbdadm create-md r0  
  
[root@drbd2 ~]# drbdadm create-md r0

HEAR BEAT Setup for 2 nodes (drbd1 , drbd 2)

[root@drbd1 ha.d]# vi ha.cf

logfacility local0
keepalive 2
#deadtime 30 # USE THIS!!!
deadtime 10
bcast eth2
#serial /dev/ttyS0
#baud 19200
auto_failback off
node drbd1.isb.ots.com drbd2.isb.ots.com

[root@drbd1 ha.d]# vi /etc/ha.d/haresources

drbd1.isb.ots.com IPaddr::10.0.0.5/27/eth0 drbddisk::r0 Filesystem::/dev/drbd0::/data::ext3

SAME configuration on node 2 with different name and IP

root@drbd1 ~]# cat /proc/drbd  
version: 8.3.2 (api:88/proto:86-90)  
GIT-hash: dd7985327f146f33b86d4bff5ca8c94234ce840e build by mockbuild@v20z-x86-64.home.local, 2009-08-29 14:02:24  

[root@drbd2 ~]# cat /proc/drbd  
version: 8.3.6 (api:88/proto:86-91)  
GIT-hash: f3606c47cc6fcf6b3f086e425cb34af8b7a81bbf build by root@drbd2.isb.ots.com, 2009-11-10 08:57:54

[root@drbd1 ~]# /etc/init.d/drbd start  
Starting DRBD resources: [ d(r0) s(r0) n(r0) ]....  

[root@drbd1 ~]# cat /proc/drbd  
version: 8.3.2 (api:88/proto:86-90)  
GIT-hash: dd7985327f146f33b86d4bff5ca8c94234ce840e build by mockbuild@v20z-x86-64.home.local, 2009-08-29 14:02:24  
0: cs:WFConnection ro:Secondary/Unknown ds:Inconsistent/DUnknown C r----  
ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:200736  

[root@drbd2 ~]# /etc/init.d/drbd start  
  
[root@drbd2 ~]# cat /proc/drbd  
version: 8.3.6 (api:88/proto:86-91)  
GIT-hash: f3606c47cc6fcf6b3f086e425cb34af8b7a81bbf build by root@drbd2.isb.ots.com, 2009-11-10 08:57:54  
0: cs:Connected ro:Secondary/Secondary ds:Inconsistent/Inconsistent C r----  
ns:0 nr:0 dw:0 dr:0 al:0 bm:0 lo:0 pe:0 ua:0 ap:0 ep:1 wo:b oos:200736

[root@drbd1 ~]# drbdadm  -- --overwrite-data-of-peer primary  r0  
  
[root@drbd1 ~]# cat /proc/drbd  
version: 8.3.2 (api:88/proto:86-90)  
GIT-hash: dd7985327f146f33b86d4bff5ca8c94234ce840e build by mockbuild@v20z-x86-64.home.local, 2009-08-29 14:02:24  
0: cs:SyncSource ro:Primary/Secondary ds:UpToDate/Inconsistent C r----  
ns:70656 nr:0 dw:0 dr:70656 al:0 bm:4 lo:0 pe:100 ua:0 ap:0 ep:1 wo:b oos:133280  
[======>.............] sync'ed: 36.0% (133280/200736)K  
finish: 0:00:15 speed: 8,432 (8,432) K/sec

For Node 3

Now add 3rd node resource on /etc/drbd.conf

}  
resource r1 {  
protocol A;  
syncer {  
after r0;  
rate 12M;  
al-extents 513;  
}  
net {  
}  
stacked-on-top-of r0 {  
device /dev/drbd3;  
address 192.168.1.224:7788; # Virtul of 2 node DRBD clusterIP provided by Heartbeat  
}  
  
on drbd3.isb.ots.com {  
device     /dev/drbd3;  
disk       /dev/hda5;  
address    192.168.1.225:7788; # Public IP of the backup node  
meta-disk  internal;  
}  
}  

[root@drbd1 ~]# drbdadm --stacked create-md r1  
  
[root@drbd1 ~]# drbdadm --stacked up r1  
  
[root@drbd1 ~]# drbdadm --stacked -- --overwrite-data-of-peer primary  r1  
  
[root@drbd3 ~]# drbdadm create-md r1  

root@drbd3 ~]# cat /proc/drbd  
version: 8.3.2 (api:88/proto:86-90)  
GIT-hash: dd7985327f146f33b86d4bff5ca8c94234ce840e build by mockbuild@v20z-x86-64.home.local, 2009-08-29 14:02:24

3: cs:SyncTarget ro:Secondary/Primary ds:Inconsistent/UpToDate A r—-
ns:0 nr:40524 dw:37720 dr:0 al:0 bm:1 lo:702 pe:0 ua:701 ap:0 ep:1 wo:b oos:162972
[===>…………….] sync’ed: 20.5% (162972/200692)K
finish: 0:00:17 speed: 9,428 (9,428) K/sec
[root@drbd3 ~]#