This document describes migrating a database from a standalone MySQL configuration to a Galera cluster for high availability and redundancy. It outlines the existing infrastructure including web, mail, and database servers managed by Puppet. It then details removing the existing MySQL data and joining the nodes to the new Galera cluster. Configuration files are shown for Galera settings like the state snapshot transfer method and slave threads. System information is displayed for one of the Galera nodes including the large production database size and high query throughput. The GitHub link shows example Puppet code to check the Galera cluster status and return errors if not in the primary or connected states.

2. http://bit.ly/olindata-galera-migration

5. Puppet Master
Puppet Code
(.git repository)
web01.olindata.com mail01.olindata.comdb01.olindata.com
Puppet Agent Puppet AgentPuppet Agent

10. rm -rf /var/lib/mysql

11. http://bit.ly/olindata-galera-migration

12. Galera Node 1
(Writes + some reads)
Galera Node 2..6
(Read only traffic)
haProxy Active haProxy Passive
web application
servers
(MS Windows)
FOSS Puppet 3.7.5 +
R10K + mco
port 13306
port 13307

13. root@maurycity:~# pt-summary
# Percona Toolkit System Summary Report ######################
Uptime | 265 days, 21:57, 1 user, load average: 3.06, 3.20, 3.22
System | Dell Inc.; PowerEdge R320; vNot Specified (Rack Mount Chassis)
Platform | Linux
Release | Debian GNU/Linux 7.8 (wheezy) (wheezy)
Kernel | 3.2.0-4-amd64
# Processor ##################################################
Processors | physical = 1, cores = 6, virtual = 12, hyperthreading = yes
Speeds | 12x2199.748
Models | 12xIntel(R) Xeon(R) CPU E5-2430 0 @ 2.20GHz
Caches | 12x15360 KB
# Memory #####################################################
Total | 63.0G
Free | 15.2G
Used | physical=47.8G, swap allocated=1.9G, swap used=228.9M, virtual=48.1G

14. #wsrep_% variables
| wsrep_sst_method | xtrabackup-v2
| wsrep_slave_threads | 16
#gcache
gcache.size = 1024M;
#/etc/mysql/conf.d/wsrep.cnf
root@maurycity:~# cat /etc/mysql/conf.d/wsrep.cnf
[mysqld]
# (This must be substituted by wsrep_format)
binlog_format=ROW
# Query Cache is not supported with wsrep
query_cache_size=0
query_cache_type=0
wsrep_provider_options=gcache.size=1024M

15. # How many threads will process writesets from other nodes
wsrep_slave_threads=16
# change auto_increment_increment and auto_increment_offset automatically
wsrep_auto_increment_control=1
# notify external systems
wsrep_notify_cmd=/usr/local/galeranotify/galera_notify.sh
# State Snapshot Transfer method
wsrep_sst_method=xtrabackup-v2
# SST authentication string. This will be used to send SST to joining nodes.
# Depends on SST method. For mysqldump method it is root:<root password>
wsrep_sst_auth=sst_xtrabackup:likeimgonnashowthathere

16. [sst]
# Xbstream is highly recommended. Refer to http://www.percona.com/doc/percona-xtradb-
cluster/5.6/manual/xtrabackup_sst.html#tar-ag-xbstream
# for details and caveats of using tar v/s xbstream for SST.
streamfmt=xbstream
# If equal to:
# 1 it writes to mysql stderr
# path/to/file writes to that file. If this is a fifo, it needs to exist and be open on
reader end before itself,
# otherwise wsrep_sst_xtrabackup will block indefinitely.
progress=1
# Enabling it instruments key stages of backup/restore in SST.
time=1

17. mysql {giltedge} >s
--------------
Server version: 5.6.22-72.0-56 Percona
XtraDB Cluster (GPL), Release rel72.0,
Revision 978, WSREP version 25.8, wsrep_25.8.
r4150
Uptime: 140 days 19 hours 30 min 22 sec
Threads: 96 Questions: 2256269807340 Slow
queries: 80145 Opens: 127115258 Flush
tables: 1 Open tables: 2000 Queries per
second avg: 185453.611 x6 ≈ 1.100.000(!)

18. mysql {giltedge} >SELECT table_schema "Data Base Name",
-> sum( data_length + index_length ) / 1024 / 1024 "Data Base Size in MB",
-> sum( data_free )/ 1024 / 1024 "Free Space in MB"
-> FROM information_schema.TABLES
-> GROUP BY table_schema ;
+--------------------+----------------------+------------------+
| Data Base Name | Data Base Size in MB | Free Space in MB |
+--------------------+----------------------+------------------+
| information_schema | 0.00976563 | 0.00000000 |
| mysql | 3.77337646 | 4.18228531 |
| performance_schema | 0.00000000 | 0.00000000 |
| production | 240352.62500000 | 23461.00000000 |
| test | 113.87500000 | 35.00000000 |
[..]
+--------------------+----------------------+------------------+

19. http://bit.ly/olindata-galera-migration

21. # https://github.com/olindata/puppet-galera/blob/5b6fc8d0c79e7b19ec167a17e79fcfccdf459e6d/templates/clustercheck.erb#L130
# if state is not 2 or 4, return an error
if [ $wsrep_local_state -ne 4 ] && [ $wsrep_local_state -ne 2 ]; then
return_fail "State of wsrep_local_state is not 2 or 4, but '${wsrep_local_state}'";
fi
# is wsrep_connected set to ON?
if [ "$wsrep_connected" != "ON" ]; then
return_fail "State of wsrep_connected is not ON, but '${wsrep_connected}'"
fi
# is wsrep_cluster_status set to Primary?
if [ "$wsrep_cluster_status" != "Primary" ]; then
return_fail "State of wsrep_cluster_status is not Primary, but '${wsrep_cluster_status}'"
fi
# is wsrep_ready set to ON?
if [ "$wsrep_ready" != "ON" ]; then
return_fail "State of wsrep_ready is not ON, but '${wsrep_ready}'"
fi
# is wsrep_cluster_state_uuid equal to wsrep_local_state_uuid?
if [ "$wsrep_cluster_state_uuid" != "$wsrep_local_state_uuid" ]; then
return_fail "Value of wsrep_cluster_state_uuid ('${wsrep_cluster_state_uuid}') does not match wsrep_local_state_uuid
('${wsrep_local_state_uuid}')"
fi