2013/03/23 Chiba.pm #2の資料です。 辞書首っ引きで書いたので英語はかなりテキトーです。 日本語に直そうとしたら機械翻訳っぽくなったのでやめました。

1. XtraDB Cluster
Chiba.pm #2 at 2013/03/23
yoku0825

2. ＼こんにちは！／
• I’m yoku0825, working as DBA for the
company’s web services.
• Husband of my wife :)
• Father of my sun :)
• I love MySQL too match, such as I can’t log-in
PostgreSQL and Oracle :(
• Maybe Perl Monger, seldom wrote codes but!!

3. Today, I talk about
Percona XtraDB Cluster

4. Today, I talk about
Percona XtraDB Cluster
ぺるこな
えくすとらでぃーびーくらすたー

5. Do you know Percona LLC?
Famous their work are Percona-Toolkit,
for MySQL Utility Tools,
and Percona-Server,
extended MySQL clone.
http://www.percona.com/

6. XtraDB Cluster is implementation of
Galera Replication by Percona LLC.
What’s Galera Replication?
ATO-DE-MATA-DETEKIMASU.

7. 取り敢えず響きが良いですよ
ね
エクストラディービークラスター

8. ベンチマーク無双してる頃に
会社の食堂に行って

9. 「あ、XtraDB」
「えっ」
「ホットで」
「えっ」
「えっ」

10. orz

11. くらい、響きが良いですよ
ね :D
XtraDBだけだと
ストレージエンジンの
名前なんですけどね

12. Percona XtraDB Cluster
Clustered by
– Multi Master
– (Virtual) Synchronous
– Parallel in Row-Level
Write Set Replication(wsrep)
So it makes flat(no nodes are specific as Master or Slave)
MySQL Replication topology.
And wsrep takes a automated Full-physical and
Increment-logical data synchronization.

13. wsrep
• wsrep is the concept for realize following notes(following
next page)
– wsrep implementation by cordership named Galera
Replication, it takes the form of patch for MySQL(there is
implementation for PostgreSQL, but I don’t know about that).
And MySQL compiled with Galera Replication patch is
destributed by cordership, named Galera Cluster for MySQL.
• http://www.codership.com/content/using-galera-cluster
– Percona-Server compiled with Galera Replication patch is
named Percona XtraDB Cluster.
• http://www.percona.com/software/percona-xtradb-cluster
– MariaDB compiled with Galera Replication patch is named
MariaDB Galera Cluster.
• https://kb.askmonty.org/en/what-is-mariadb-galera-cluster/

14. Multi Master
• All nodes are writable
– Of cource, standard MySQL Replication is so.
– But you write into table on Replication Slave, its
updates(INSERT, UPDATE, DELETE, and so) are not
replicated to any node without its own Slave Server.
This means it breaks consistency, so we can’t allow to
write Replication Slave by read_only option variable.
– wsrep library certs consistency when you write into
table on any node by using (Virtual) Synchronous
Replication.

15. (Virtual) Synchronous
• All nodes have same data (DAI-TAI) anytime
– When you write some data into some node, wsrep library
hooks InnoDB API and writes wsrep’s binary log(Galera
Cache) in row-based binary log, before it answers commit
request.
– Galera Cache is pushed through Communication-Path and
confirmed “Can it execute with integrity, without conflict
of update?” on all other nodes.
– When wsrep gets that confirmation(Certification) on all
other nodes, its update is committed at last.
Otherwise, when wsrep received Certification Failure, its
transaction will rollback(=return Error: 1213 “Deadlock found
when trying to get lock.”) and any node doesn’t update to
keep consistency.

16. (Virtual) Synchronous
• Why it called “Virtual” Synchronous?
– It has a little rag between Certification and Real-
Write into Disk.
– The server which is received to write request at
first writes its data into disk and notifies “its data
is committed”. All other servers can write into disk
after that notification(because of keeping it
transaction can rollback)

17. Parallel in Row-Level
• Any updates logged in Galera Cache is Row-Based
Binary log
– It makes each Certification is isolated in Row-Level, it
makes each Certification can work in multi thread.
– Statement-Based Replication can’t detect even if
replication has lost data consistency. Do you face
Error:1032 “Can’t find record in `tablename`”?
• Not only Galera Cache, but also “binary log” for using
standard replication.
– It inherits some weakpoint of standard RBR.
• MySQL 5.6 improves Multi Thread SQL_Thread but it
works only separated Database-Level.

18. State Snapshot Transfer(SST)
• It is full data copy from joined cluster node to joining
cluster node, automated by wsrep library.
– You can choise “rsync”(physical copy, need
lock), “mysqldump”(logical copy, need lock too), “custom
script”.
– XtraDB Cluster can use xtrabackup(physical copy, without
lock) as “custom script”. It makes adding new node and
coming back downed node are lock-free and almost
automation.
• If wsrep detects “impossible(=can’t certificate) update”
why data is mismatch just then wsrep execute SST and
keeps consistency over the cluster.

19. Incremental State Transfer(IST)
• It is incremental data copy from joined cluster
node to joining cluster node, automated by wsrep
library.
– When cluster node leave and come back shortly,
wsrep doesn’t need SST if they have enough Galera
Cache covered all over its downtime.
– IST doesn’t need any locks and need any reads
physical data file, because of IST uses only Galera
Cache. And Galera Cache is maybe hot cache ‘coz it is
“nearest updates for cluster”, IST is very faster than
SST.

20. Flat Topology + Automated SST =
• You don’t be annoyed at all, when
– “OMG! Master is down! Get to switchover now!”
• There’s nothing to do you’ve already prepared your LVS
configure.
– “OMG! There is some different data between Master
and Slave!”
• wsrep have already fixed it before you know that, you can
see only the fact SST is done.
– “OMG! Today is Christmas but I don’t have Girlfriend!”
• I’m very veeeeery sorry. If I don’t introduce XtraDB
Cluster, you can keep you don’t know that.

21. Combination with
Standard Replication
• wsrep hooks only InnoDB write method, it means
wsrep is separated from MySQL standard Replication.
– Each node joining XtraDB Cluster can be Slave of another
mysqld.
– Any mysqld can be Slave of node joining XtraDB Cluster.
– But XtraDB Cluster Node doesn’t have binary log for
update through Galera Cache and inside out, you have to
put log-slave-updates in your my.cnf.
– And you have to know, wsrep doesn’t
support(correctly, “does ignore”) except of updates into
InnoDB.

22. How is it?
Do you feel something WAK-WAK?

23. 勿論弱点も(いっぱい)ありま
す
I/Oに負荷が偏るとか
wsrepの部分の日本語情報少ないとか
xtrabackupと連携させるのにinnobackupexいじるとか
xtrabackup使わないとSSTでリードロックかかるし
RBR前提なのでバイナリログでっかいとかPrimary Keyが無いと悲惨とか
更新がかかったノードにしかバイナリログ無いとか
InnoDB(XtraDB)以外のデータはそもそも同期されないとか

24. 性能は？
tpcc-mysqlで叩いた感じ、Semi-Sync(M/S)の3割引くらいでした
ネットワーク帯域とかバイナリログの保管場所にも注意
LVS通した分のオーバーヘッドもたぶんある
パラレルレプリケーションする為にそれなりのコアが必要
(1行が1スレッド使うから、1万行更新するクエリは…)
サーバまたぎの更新がlock waitじゃなくてCertification Failure(=Deadlock扱い)になるの
で、
アプリ側でハンドルしてやらないといけない

25. ( ´-｀).oO（難易度的には
ndbcluster(=MySQL
Cluster)と
良い勝負かな）
異論はあると思う

26. でも楽しそうですよね！
何より響きが良い

27. ところでみなさん
お気付きでしょうか

28. 実はこれ、Perlの話じゃないんで
す
“Percona” =~ /^Per/
But
“Percona” != “Perl”

29. Chiba.pm #1 で話していた
書き捨てMySQLモニターツー
ル
https://github.com/yoku0825/my_collector

30. 挫折しましたorz
だってCactiあるんだもん

31. でもたまに役に立ちます
Cactiよりドリルダウンしたいとき
金曜日に地味に機能追加してみたりした
スローログ数えるやつも地味に使ってる
https://github.com/yoku0825/my_slowlog

32. あ、あと

33. この前MyNA会で
「俺はVimmer」って言いました
が

34. あれは嘘です
嘘っていうか、
Vimしか使えない消極的Vimmer
.vimrcもgtags関連しか入れてない

35. Terapad最高！
Perlスクリプトもてらぱで書く

36. ご清聴ありがとうございました
オチなし