This document discusses using Pacemaker, Corosync and DRBD to provide high availability for MySQL databases in an OpenStack cloud environment. It presents the technical objectives of providing active-passive database HA, data persistence with DRBD, monitoring MySQLd with Corosync, and floating the IP address when failures occur using Pacemaker. Sample configurations are shown for Corosync and Pacemaker to configure the HA cluster.

1. An High Available Database
for OpenStack Cloud Production
by Pacemaker, Corosync & DRBD
@j3ffyang, Jeffrey Yang, OpenStack Dev, IBM
OpenStack Summit, Atlanta, 2014

2. Technical Objective
●
Database high availability (active - passive)
●
Data persistence (drbd)
●
MySQLd monitored (corosync)
●
IP address floating when failure occurs
(pacemaker)

3. High Level Architecture
DRBD
MySQL
Corosync
Pacemaker
DRBD
MySQL
sync
Compute
Other OpenStack components

4. Sample Configurations
[root@host10 corosync]# cat corosync.conf
...
totem {
version: 2
token: 10000 # 10 seconds
token_retransmits_before_loss_const: 10
secauth: on
threads: 0
interface {
ringnumber: 0
bindnetaddr:10.10.203.0
mcastaddr: 226.94.1.1
mcastport: 5405
ttl: 1
}
}
logging {
fileline: off
to_stderr: no
to_logfile: yes
to_syslog: yes
logfile: /var/log/cluster/corosync.log
debug: off
timestamp: on
logger_subsys {
subsys: AMF
debug: off
}
}
...
service {
ver: 0
name: pacemaker
use_mgmtd: yes
}
[root@host10 corosync]# crm configure edit
node host10
attributes standby="off"
node host20
attributes standby="off"
primitive drbd_mysql ocf:linbit:drbd
params drbd_resource="mysql"
op monitor interval="29s" role="Master"
op monitor interval="31s" role="Slave"
primitive fs_mysql ocf:heartbeat:Filesystem
params device="/dev/drbd1" directory="/opt/drbd/" fstype="ext4"
primitive ip_mysql ocf:heartbeat:IPaddr2
params ip="10.10.203.19" nic="eth3"
primitive mysqld lsb:mysqld
group mysql fs_mysql ip_mysql mysqld
ms ms_drbd_mysql drbd_mysql
meta master-max="1" master-node-max="1" clone-max="2" clone-node-max="1"
notify="true"
colocation mysql_on_drbd inf: mysql ms_drbd_mysql:Master
order mysql_after_drbd inf: ms_drbd_mysql:promote mysql:start
property $id="cib-bootstrap-options"
dc-version="1.1.7-6.el6-148fccfd5985c5590cc601123c6c16e966b85d14"
cluster-infrastructure="openais"
expected-quorum-votes="2"
stonith-enabled="false"

5. Demo
●
Captured from a production environment at
one of IBM customers
●
https://www.youtube.com/watch?v=UEln0TUU
aH8

6. To- do
●
Enhance cookbook for automatic deployment
(DevOps)
●
Move to Galera Cluster for multi- nodes (all
active)