SQL Server AlwaysOn (HADRON)

Transcription

1 SQL Server AlwaysOn (HADRON) 朱 桦 Technical Leader, Microsoft Database Support Team Microsoft Public - See Terms of Use

2 2 Windows Server Failover Clustering (WSFC) Shared Data Disk Multi-node w/shared Data Storage SQL Binaries on each node Client Connections via Virtual Server Name Manual or Automatic Instance Failover Stretch Cluster via VLAN AlwaysOn Failover Cluster Instances (FCI) Flexible Failover Policy sp_server_diagnostics logging Multi-Subnet Failover Cluster Faster Recovery with Indirect Checkpoints

3 3 Log Shipping Provides Remote Disaster Recovery Site Database Level Protection Based on Transaction Log Backup\Restore Easy to setup No Automatic Failover No Client Redirection

4 4 Database Mirroring Hot Disaster Recovery Site for Single Database Easy setup using Wizard per Database Synchronous Mirroring Automatic Failover via 3rd Witness Server Client Redirection Asynchronous Mirror Automatic Page Repair (2008) Log Stream Compression (2008) Mirror Backups (2008)

5 5 New for SQL Server 2012 Log Shipping + Database Mirroring + Windows Clustering = AlwaysOn Availability Group for Database Protection Primary Replica Data Changes Synchronous Hot DR Standby Asynchronous Warm Standby Readable Reports Asynchronous Warm Standby Readable Backups

6 6 from Windows Server Failover Cluster (WSFC) Automatic Failover via Windows Server Failover Cluster (WSFC) Flexible Failover Policy using sp_server_diagnostics Multisite Clustering using disbursed servers Multiple Secondary Nodes (up to four) Virtual Server Name for Client Redirection (availability group listener) Enhanced No shared disk storage used in Windows Clustering No restart of SQL resulting in faster failover Failover single, or group of databases instead of entire SQL Server

7 7 from Database Mirroring Two Synchronous Secondary Servers for high availability Backup Asynchronous Secondary Servers (total 4) Automatic Bi-Directional Page Repair Secondary Backup (SQL 2008 EE) Enhanced Log Backup maintains backup chain allowing restore to Primary Maintenance Plans preferred backup based on priority Bi-directional automatic page repair 7

8 8 SQL Server 2012 Management Studio Availability Group Participating SQL instances, their roles and corresponding properties Availability Replica Unit of failover. Single database or group of databases Group Listeners Single Name Connection

9 AlwaysOn Architecture Windows Server Failover Clustering (WSFC) Cluster Network Subnet Network Subnet Node Node Node Node Node WSFC Configuration WSFC Configuration WSFC Configuration WSFC Configuration WSFC Configuration SQL Server Instance SQL Server Instance SQL Server Instance SQL Server Failover Cluster Instance Instance Network Name Instance Network Name Instance Network Name Instance Network Name AlwaysOn Availability Group Primary Replica Secondary Replica Secondary Replica Secondary Replica AG Listener Virtual Network Name Storage Storage Storage Shared Storage WSFC Quorum Witness Remote File Share 9

10 Availability Group Configuration Up to 5 replicas (including primary) Availability Mode Asynchronous Synchronous Up to 3 replica per availability group including primary Failover mode Manual Automatic Up to 2 per availability group Requires synchronous availability mode Readable Secondary No Yes Read Intent 10

11 11 AVAILABILITY GROUP AVAILABILITY MODE Asynchronous Primary replica doesn t wait for secondary replicas to harden log records. Performance over data protection Secondary never synchronized / can lag behind Reports synchronizing, never synchronized Useful When availability replicas are distributed Transaction performance is priority Synchronous Primary commit waits for secondary log harden Synchronized data protection over performance High availability over performance Reports synchronizing or synchronized

12 12 AVAILABILITY GROUP FAILOVER MODE AUTOMATIC Requires synchronous availability mode Up to two availability replica Additional configuration options HEALTH_CHECK_TIMEOUT FAILURE_CONDITION_LEVEL MANUAL Asynchronous or synchronous availability mode

13 13 Types of Failover Three Types of Failover Automatic Synchronous Commit Automatic Failover Replica in SYNCHRONIZED state Planned manual failover (without data oss) No data loss - supported when synchronous commit and secondary is synchronized alter availability group agtest1 failover Forced manual failover (with possible data loss) Supported with asynchronous commit Secondary is synchronizing or not_synchronized alter availability group agtest1 force_failover_allow_data_loss

14 14 AlwaysOn Readable Secondaries Secondary Replica is Active Offload Read Only activity Backups DBCC CHECKDB Read Only querying, reporting How do you re-direct read-only activity?

15 AlwaysOn Readable Secondaries Configure secondary for read access CREATE AVAILABILITY GROUP REPLICA ON SQL01' WITH ( SECONDARY_ROLE= ) - NO - ALL - READ_ONLY 15

16 AlwaysOn Readable Secondaries Read-Only client connection behavior determined by Availability Replica Option+ ApplicationIntent Property READ ONLY ROUTING 1. Secondary replica read access SECONDARY_ROLE 2. Set replica s URL for secondary routing READ_ONLY_ROUTING_URL 3. When primary, replica routing list READ_ONLY_ROUTING_LIST 4. Application connects using listener 5. Application use ReadOnly to connect 16

17 AlwaysOn Backup on Secondary Why backup on secondary? Backup is resource intensive Offload job from Tier-1 application What is supported: BACKUP DATABASE (copy-only full backup) BACKUP LOG Differential not supported Offload backups to synchronized or synchronizing secondaries Manage backups with new Recovery Advisor 17

18 Mulit-Subnet Failover No VPN needed No storage replication Multi IP address OR dependency 18

19 Keywords for Multi-Subnet AG RegisterAllProvidersIP - Get rid of DNS issue MultiSubnetFailover - Quick establish connection 19

20 20