MySQL High Availability

Transcription

1 MySQL High Availability And other stuff worth talking about Peter Zaitsev CEO Moscow MySQL Users Group Meetup July 11 th,

2 Few Words about Percona 2

3 Percona s Purpose To Champion Unbiased Open Source Database Solutions 3

4 We Do Support, Managed Services for MySQL and MongoDB Also Consulting and Training Helping companies to migrate to Open Source Database Develop Open Source Software Solutions to maximize your success 4

5 Broad Software Ecosystem Support MySQL Percona Server MariaDB Percona XtraDB Cluster Galera Cluster for MySQL MariaDB Galera Cluster MongoDB Percona Server for MongoDB Amazon RDS for MySQL/MariaDB/Aurora Google CloudSQL 5

6 100% Free and Open Source Software Percona Server for MySQL Percona Server for MongoDB Percona XtraDB Cluster Percona Xtrabackup Percona Toolkit Percona Monitoring and Management 6 6

7 MySQL High Availability 7

8 What is High Availability What Do you Think? 8

9 I think Serving All the Clients Correctly all the Time 9

10 Performance and High Availability Unacceptable performance can be indistinguishable from downtime 10

11 High Availability is Never Perfect Can be measured in terms of time where system was available Can be measured in the terms of successful requests served 99.9% or 3 nines Good to consider cases of partial availability 11

12 Is Perfect High Availability the Goal? Booking.com has the downtime budget 12

13 To have Good High Availability Go down less Recover faster 13

14 Not a Database Problem Systems Problem But Database is the key component 14

15 Achieving High Availability Technology Aspects Process Aspects 15

16 Technology Aspects Designing and Building Highly Available System 16

17 Technology Aspects Focus on Technology in this presentation, it is what MySQL Specific 17

18 Process Aspects Managing System in Highly Available way 18

19 Process General Best Practices Quality Assurance for Code and Operations Practices Tables and Query Review Performance Testing Capacity Planning Clear Roll Back Process Being able to disable feature live On Call for devs and ops 19

20 High Availability through Redundancy Server Redundancy Network Redundancy Data Center Redundancy 20

21 Stateless vs Stateful for HA Stateless Multiple instances High Availability is easy Stateful Need to Maintain state in highly available fashion Much harder problem 21

22 Database are Stateful 22

23 High Level Thoughts Lets think about database as a black box 23

24 HA Concerns for Databases Durability What kind of guarantees do I have about my data being persisted Change Visibility How my changes are propagated and become visible? Failure Handling Which failures system is designed to handle and how it reacts Performance HA is never free. How are we paying for guarantees 24

25 Replication With Stateful Systems HA requires maintaining multiple copies of data 25

26 Focus Focus on Database Engine level Replication as Most Common 26

27 Things To Consider How Replication is Happening Who and How Detects Failure Mechanics of Failover and Recovery 27

28 MySQL Options 28

29 MySQL Options to Consider MySQL Replication MySQL Group Replication Galera and Percona XtraDB Cluster 29

30 MySQL Replication Standard MySQL Replication 30

31 Classic MySQL Replication Fully Asynchronous No Failure Detection and Promotion Manual Provisioning Can run Multi-Master No Conflict Handling 31

32 Semi-Synchronous Is Asynchronous One of the Slaves gets a copy before commit succeeds on the Master 32

33 GTID Old Style MySQL Replication Position identified by Binary Log file and Offset Different on different nodes in Replication Topology Simple GTID Each transaction gets an identifier Nodes know what transactions they Executed GTID same in the Replication Topology Hard 33

34 MySQL Replication Topologies Master can have any number of Slaves Can replicate everything or part of data set You can cascade replication with no limits You can create replication loops (through not recommended) Starting MySQL 5.7 slave can source from multiple masters 34

35 MySQL Replication Performance Single Thread in MySQL 5.5 and Belog Thread per database in MySQL 5.6 Multi-Threaded (even single table) in MySQL

36 Making MySQL Replication Better MHA MySQL Failover Orchestrator 36

37 Orchestrator Screenshot 37

38 PMM Dashboard for Replication 38

39 MySQL Group Replication And Innodb Cluster 39

40 MySQL Group Replication Overview Inspired by Galera Ideas (and Success) Built on top of standard MySQL Replication Available as Plugin for MySQL 5.7 Considered GA but really very early product 40

41 Difference from MySQL Replication No Master/Slave but Group Membership Transactions are committed when they are certified by majority of nodes (Paxos) Does not accept writes if there is no Quorum Flow Control to prevent unlimited replication lag Nodes encountering inconsistency leave the cluster Conflict Detection and Resolution (or avoidance) Simple FailOver 41

42 MySQL Group Replication - Writes By Default configures itself as Single Primary Can configure to allow writes to any node 42

43 MySQL Group Replication Limitations No Automated node Provisioning Manual Recovery of failed nodes No way (yet) to ensure node does not read stale data 43

44 MySQL Innodb Cluster 44

45 MySQL Innodb Cluster Really MySQL Group Replication MySQL Shell (for configuration) MySQL Router for traffic management 45

46 Percona XtraDB Cluster and Galera 46

47 Percona XtraDB Cluster Virtually Synchronous Replication Well known Innodb Storage Engine All Reads are Local Parallel Replication Write to any node behavior Built in Node Provisioning and HA Works great in the Cloud! 47

48 PXC vs Galera Galera Is replication technology/library Compare to Linux Kernel Percona XtraDB Cluster Percona Server Enabling Enhancements Galera Library Provisioning Tools HA and Load Balancing Integrated together and Tested Compare to Linux Distribution 48

49 PXC Data Architecture 49

50 Architecture Concepts All Nodes Have Full copy of Data Every Node is Equal No Central Management No SPOF 50

51 Cluster Reads Reads are always Local Stale Reads can be allowed or disallowed 51

52 Cluster Writes Write on one node or Write Anywhere Certification Based Replication Communication on Commit only Asynchronous Application Parallel Replication 52

53 Transaction Commit Flow 53

54 Quorum 5 4 Loss of connectivity Network Problem Does not accept Reads & Writes 54

55 Automatic Node Provisioning 5 5 new node joining writes writes writes 55

56 Automatic Node Provisioning 5 6 when ready new node joining writes writes writes writes 56

57 Traffic Management Solutions DNS HAProxy Elastic Load Balancer (etc) MySQL Router MaxScale, ScaleArc ProxySQL Not Immediate, Does not handle existing connections TCP/IP Port level. Does not understand MySQL Protocol Like HA Proxy in the Cloud Currently very basic Proprietary Solutions MySQL Protocol Aware 100% Open Source Proxy Solution for MySQL 57

58 We integrate ProxySQL with PXC High Availability Multiplexing (Connection Pooling) Caching Read/write Splitting Easy Configuration with proxysql-admin Can run in dedicated writer and load balanced mode 58

59 Dedicated shared ProxySQL 5 9 application server 1 application server 2 application server 3 ProxySQL PXC node 1 PXC node 2 PXC node 3 59

60 ProxySQL on application side 6 0 application server 1 application server 2 application server 3 ProxySQL ProxySQL ProxySQL PXC node 1 PXC node 2 PXC node 3 60

61 ProxySQL with PMM 61

62 Percona XtraDB Cluster 5.7 pxc_safe_mode to prevent you from visiting encrypt_pxc_traffic Easy to use Cluster Traffic Encryption Instrumentation with Performance Schema Better Usability Faster SST Better general Performance 62

63 PXC 5.7 Performance Improvements and 63

64 PXC at PMM 64

65 Scaling Writes? Shard over PXC Cluster rather than MySQL Replicas 65

66 Things To Keep in Mind Use Innodb storage engine Primary Key on all tables Avoid Large write transactions (changing many rows) Plan Data size for SST time correctly Hot Rows Optimistic Locking 66

67 PXC vs MySQL Group Replication Great Webinar by Kenny Gryp 67

68 Some Unrelated but Wonderful Topics 68

69 Percona Monitoring and Management 69

70 Percona Monitoring and Management 100% Free and Open Source Comprehensive Database focused Monitoring Supports MySQL and MongoDB (and variants) Easy to Install and Use Version 1.x focuses on Trending and Query Analyses Management Features to come 70

71 Why did we created PMM No good database focused monitoring solution Existing solutions Proprietary or Cloud Only Do it yourself is possible but hard Want everyone to be able to run monitoring in every environment To fix problems before they appear 71

72 What Queries are causing the load? 72

73 Why are they causing this load? 73

74 How to fix them 74

75 System Information 75

76 What happens on OS and Hardware Level 76

77 As well as Database Level 77

78 Best to check out Demo 78

79 79

80 Have a Friend? Refer a friend and get $1000 if one is hired by Percona and eternal gratitude for helping to get the most amazing job 80

81 Percona Live Europe Call for Papers & Registration are Open! Championing Open Source Databases MySQL, MongoDB, Open Source Databases Time Series Databases, PostgreSQL, RocksDB Developers, Business/Case Studies, Operations September 25-27th, 2017 Radisson Blu Royal Hotel, Dublin, Ireland Submit Your Proposal by July 17 th! 81

82 Thank You! Peter Zaitsev P.S We re Hiring

83 DATABASE PERFORMANCE Database Performance Matters MATTERS