MariaDB Galera Cluster in a master-Master Sync Replication configuration.

1. HA&Solu4ons&for&MySQL&
Joffrey&Michaie&
Consultant&
SkySQL&AB&©&2013&Confiden4al&

2. Agenda&
• Introduc4on&
• MySQL&Replica4on&
• SemiHSynchronous&Replica4on&
• MySQL&5.6&
• MariaDB&10.0&
• MHA&
• Galera&
• Shared&Disk&
• DRBD&
• MySQL&Cluster&
SkySQL&AB&©&2013&Confiden4al&

3. Introduc4on&to&HA&
“High&availability&is&a&system&design&protocol&and&
associated&implementa6on&that&ensures&a&certain&
degree&of&opera6onal&con6nuity&during&a&given&
measurement&period”&
SkySQL&AB&©&2013&Confiden4al&

4. Up4me,&Down4me,&9s&
Availability&=&up4me&/&(up4me&+&down4me)&
&
&90%& &
&
&
&
&1&nine&&
&
&
&36.5&days&/&year &&
&
&99%& &
&
&
&
&2&nines& &
&
&3.65&days&/&year&
&
&99.9%&&
&
&
&
&3&nines& &
&
&8.76&hours&/&year&
&
&99.99%& &
&
&
&4&nines& &
&
&52&minutes&/&year&
&
&99.999%& &
&
&
&5&nines& &
&
&5&minutes&/&year&
&
&99.9999%&&
&
&
&6&nines& &
&
&31&seconds&/&year&
Availability&=&MTBF&/&(MTBF&+&MTTR)&
SkySQL&AB&©&2013&Confiden4al&

5. Terminology&
• Synchronous&vs.&Asynchronous&
• SharedHDisk&vs.&SharedHNothing&vs.&SharedHMemory&
• Single&Point&Of&Failure&H&SPOF&
• Failover&vs.&Switchover&
• Split&Brain&
• Node&Fencing,&STONITH,&Quorum&
SkySQL&AB&©&2013&Confiden4al&

6. Designing&for&HA&
• Which&level&of&availability&do&I&need?&
• How&many&nines?&
• Do&I&require&no&loss&of&data?&
• Could&I&loose&some&transac4ons?&
• Will&my&users&no4ce&or&care?&
• Do&I&need&automa4c&failover&or&is&manual&switchover&ok?&
• How&do&I&test&this?&
• Can&I&provide&a&reasonable&service&when&X&is&down?&
• Replace&X&with&each&component&of&the&service&
SkySQL&AB&©&2013&Confiden4al&

7. Before&we&talk&about&solu4ons&
• A&high&availability&setup&does&not&
replace&backups&
• Check&parameters&
• flush_at_trx_commit&
• sync_binlog&
• expire_logs_day&
• binlog_format&
• sync_master_info&(on&slaves)&
• ...&
• Requirements&for&parameters&may&
change&if&using&baieryHbacked&disk&
cache&
SkySQL&AB&©&2013&Confiden4al&

8. MySQL&Replica4on&H&Asynchronous&
• Asynchronous:&3&Phases&
1. Commit&and&write&to&binlog&on&Master&
2. Ship&changes&to&relay&log&on&slave&
3. Apply&changes&on&slave&&
• Master&H>&slave&rela4onship&
• MonoHthreaded&on&slaves&un4l&MySQL&5.5&
• MySQL&5.6&allows&mul4Hthreaded&
• No&conflict&resolu4on&
• MasterHmaster&replica4on&or&circular&
replica4on&need&applica4on&logic&
&
SkySQL&AB&©&2013&Confiden4al&
Slave(s)&
Master&

9. MySQL&Replica4on&–&SemiHSynchronous&
• Added&as&a&plugin&in&MySQL®&5.5&
• Ensures&that&changes&have&been&shipped&to&
at&least&one&slave&(or&4meouts)&&
• A&COMMIT&on&the&master&waits&for&ONE&
Slave&to&acknowledge&the&transac4on&
• Important:&The&Master&does&not&wait&for&the&
Slave&to&execute&the&transac4on,&only&to&write&
it&to&the&relay&log&
• So&the&Slave&SQL&Thread&may&s4ll&lag&behind&
the&Master&and&queries&to&the&Slave&may&s4ll&
return&old&data&
• Poten4ally&adds&latency&to&queries&
SkySQL&AB&©&2013&Confiden4al&
Slave(s)&
Master&

10. MySQL&Replica4on&for&HA&
• Master&<H>&standby&master&H&manual&failover&
• Minimal&down4me&for&changes&and&upgrades&
• SemiHsynchronous&should&be&used&
• Used&in&combina4on&with&other&HA&solu4ons&
for&geographical&replica4on&
SkySQL&AB&©&2013&Confiden4al&

11. MySQL®&5.6&–&New&Replica4on&Features&
• Global&Transac4on&ID&(GTID)&
• Makes&it&easy&to&automate&failover&and&slave&promo4on&
• Replica4on&failover&and&admin&u4li4es&
• Mul4Hthreaded&slaves&
• Replica4on&event&checksums&
• TimeHdelayed&replica4on&
SkySQL&AB&©&2013&Confiden4al&

12. MariaDB&10.0&–&New&Replica4on&Features&
• Mul4Hsource&replica4on&
• Global&Transac4on&ID&(GTID)&
• Different&implementa4on&from&MySQL&5.6&
• GTID&per&domain&instead&of&server&
SkySQL&AB&©&2013&Confiden4al&

13. MHA&
Master&High&Availability&Manager&
• Automates&master&failover&and&slave&
promo4on&
• Monitors&the&master&or&can&integrate&with&
Pacemaker/Heartbeat&
• Failover&is&an&online&opera4on&
• Also&allows&manual&switchover&
• Short&down4me:&open&a&few&seconds&
• MySQLHReplica4on&consistency&
• No&performance&penalty&
• Drop&in&solu4on&on&exis4ng&deployment&
&
SkySQL&AB&©&2013&Confiden4al&

14. MHA&
Failover&Process&
1. Aiempt&to&contact&MySQL&master&server&
by&SSH&
2. If&master&server&is&alive&access&the&binary&
log&and&recover&events&
3. Find&the&slave&with&the&most&advanced&
relay&log&
4. Sync&all&slaves&to&the&latest&available&
binlog&event&
5. STONITH&master&if&necessary&
6. Promote&slave&to&master&
SkySQL&AB&©&2013&Confiden4al&

15. Galera&/&MariaDB&Galera&Cluster&
• Provides&“virtually”&synchronous&
Clients
replica4on&
• Works&with&InnoDB&
• No&slave&lag&
• Transac4ons&are&validated&by&slaves&
upon&commit&
• Cer4fica4on&and&quorum&
• Transac4ons&may&be&rolled&back&
at&this&stage&
• Mul4Hmaster&or&masterHslave&possible&
SkySQL&AB&©&2013&Confiden4al&
MySQL
MySQL
MySQL
wsrep
wsrep
wsrep
Galera Replication

16. Galera&/&MariaDB&Galera&Cluster&
• Provides&“virtually”&synchronous&
Clients
replica4on&
• Works&with&InnoDB&
• No&slave&lag&
• Transac4ons&are&validated&by&slaves&
upon&commit&
• Cer4fica4on&and&quorum&
• Transac4ons&may&be&rolled&back&
at&this&stage&
• Mul4Hmaster&or&masterHslave&possible&
SkySQL&AB&©&2013&Confiden4al&
MySQL
MySQL
MySQL
wsrep
wsrep
wsrep
Galera Replication

17. Galera&–&Transac4on&Process&
• Transac4on&is&processed&
locally&up&to&commit&4me&
Client
trx
MySQL
MySQL
MySQL
wsrep
wsrep
wsrep
Galera Replication
SkySQL&AB&©&2013&Confiden4al&

18. Galera&–&Transac4on&Process&
• Transac4on&is&processed&
locally&up&to&commit&4me&
Client
• Transac4on&is&replicated&
to&whole&cluster&
trx
MySQL
MySQL
MySQL
wsrep
wsrep
wsrep
ws
Galera Replication
SkySQL&AB&©&2013&Confiden4al&
ws

19. Galera&–&Transac4on&Process&
• Transac4on&is&processed&
locally&up&to&commit&4me&
Client
• Transac4on&is&replicated&
to&whole&cluster&
• Client&gets&OK&status&
trx
MySQL
MySQL
MySQL
wsrep
wsrep
wsrep
Galera Replication
SkySQL&AB&©&2013&Confiden4al&

20. Galera&–&Transac4on&Process&
• Transac4on&is&processed&
locally&up&to&commit&4me&
Client
• Transac4on&is&replicated&
to&whole&cluster&
• Client&gets&OK&status&
• Transac4on&is&applied&in&
slaves&
MySQL
MySQL
trx
wsrep
wsrep
Galera Replication
SkySQL&AB&©&2013&Confiden4al&
MySQL
trx
wsrep

21. SharedHdisk&Solu4on&
• Ac4ve&–&Passive&replica4on&
• Failover&requires&MySQL&crash&recovery&(and&
open&file&system&crash&recovery)&
• Combined&with&Pacemaker/Heartbeat&for&
automa4c&failover&
• Virtual&IP&most&open&used&to&fail&over&
• In&theory&the&SAN&is&a&SPOF&
SkySQL&AB&©&2013&Confiden4al&

22. DRBD®&&
• Synchronous&replica4on&(three&modes)&
• Ac4ve&–&Passive&replica4on&
• Failover&requires&MySQL&crash&recovery&(and&
open&file&system&crash&recovery)&
• Combined&with&Pacemaker/Heartbeat&for&
automa4c&failover&
• Virtual&IP&most&open&used&to&fail&over&
• STONITH&or&other&fencing&mechanism&
needed&to&avoid&splitHbrain&scenarios&
• Available&on&Linux&
SkySQL&AB&©&2013&Confiden4al&

23. DRBD®&H&Architecture&
SkySQL&AB&©&2013&Confiden4al&

24. MySQL&Cluster&H&Features&
• Synchronous&replica4on&between&
nodes&
• Through&TwoHPhase&Commit&Protocol&
• ACID&transac4ons&
• Row&level&locking&
• Shared&nothing&architecture&
• No&single&point&of&failure&
• Automa4c&failover&
SkySQL&AB&©&2013&Confiden4al&
• InHmemory&storage&
• Some&data&can&be&stored&on&disk&
• Checkpoin4ng&to&disk&for&durability&
• Two&types&of&indexes&
• Ordered&THtrees&
• Unique&hash&indexes&
• Online&opera4ons&
• Add&node&groups&
• Sopware&upgrade&
• Some&table&altera4ons&

25. MySQL&Cluster&H&Architecture&
SkySQL&AB&©&2013&Confiden4al&

26. MySQL&Cluster&H&Par44oning&
SkySQL&AB&©&2013&Confiden4al&

27. MySQL&Cluster&
Network&par44oning&protocol&
Designed&to&avoid&splitHbrain&
1. Is&at&least&one&node&from&each&node&group&present?&&
• If&not&then&the&cluster&cannot&con4nue&H&shutdown&
2. Are&all&nodes&present&from&any&node&group?&
• If&so&then&this&is&the&only&viable&cluster&H&con4nue&
3. Ask&the&arbitrator&
• The&arbitrator&decides&which&”cluster”&con4nues&
• If&the&arbitrator&is&not&available&the&cluster&will&shutdown&
SkySQL&AB&©&2013&Confiden4al&

28. Where&does&MySQL&Cluster&fit?&
• High&demands&on&availability&(5&nines)&
• You&need&write&scalability&
• You&have&3&or&more&”machines”&available&
• Where&the&queries&and&data&model&are&simple&
• When&the&data&fits&in&memory&
• When&you&have&skilled&people&
SkySQL&AB&©&2013&Confiden4al&

29. Geographical&Replica4on&
• For&geographical&(mul4Hsite)&redundacy&
synchronous&solu4ons&are&open&not&
desirable&
• Standard&Replica4on&can&be&combined&
with&any&synchronous&solu4on&locally&
• MySQL&Cluster&
• DRBD&/&shared&disk&
• Galera&
SkySQL&AB&©&2013&Confiden4al&

30. Geographical&Replica4on&
MySQL&Cluster&
• MySQL&Cluster&has&addi4onal&features&
related&to&Geographical&replica4on&
• Conflict&detec4on&and&automa4c&
resolu4on&
• Several&possible&resolu4on&methods&exist&
• Mul4ple&replica4on&channels&possible&
• Mul4Hsource&replica4on&possible&
• Binlog&injec4on&ensures&the&consitency&
of&binlogs&
SkySQL&AB&©&2013&Confiden4al&

31. Quick&Comparison&Chart&
*
SkySQL&AB&©&2013&Confiden4al&

32. Quick&Comparison&Chart&
SkySQL&AB&©&2013&Confiden4al&

33. Ques4ons?&
SkySQL&AB&©&2013&Confiden4al&

34. Thank&you!&
Joffrey&Michaie&
Joffrey.michaie@skysql.com&
SkySQL&Ab&
www.skysql.com&
www.facebook.com/skysql&
www.linkedin.com/company/skysql&
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