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AlwaysOn High Availability Windows Server Core Support Online Operations Enhancements Active Secondaries Scale Read-Only Applications Offload Backups Fast Application Failover Integrated Configuration Wizard Windows PowerShell Support AlwaysOn Dashboard Microsoft System Center Monitoring

1 The percentage reduction in patching varies & can be less based on the server roles that are enabled & the type of patches that are applied.

Multi-site Failover Cluster Instance (FCI) Multi-site Failover Cluster Instance (FCI) for HA & DR Shared Storage solution Instance Level HA Instance Level DR Doesn’t require database to be in FULL recovery model Availability GroupAvailability Group for HA & DR Non-Shared Storage solution (Group of) Database Level HA (Group of) Database Level DR DR replica can be Active Secondary Requires database to be in FULL recovery model Failover Cluster Instance Failover Cluster Instance for local HA & Availability Group for DR Combined Shared Storage and Non-Shared Storage Instance Level HA (Group of) Database Level DR DR replica can be Active Secondary Requires database to be in FULL recovery model

Availability Groups AlwaysOn Availability Groups is a new feature that enhances and combines database mirroring and log shipping capabilities Application failover using virtual name Configuration Wizard Dashboard System Center Integration Rich diagnostic infrastructure File-stream replication Replication publisher failover

TechAG1 2 DB 2DB2DB 2DB2DB PrimarySecondary TechListener1 Parameter Sample: - server TechListener1;- catalog HRDB Application retry during failover Primary Secondary 2DB2DB 2DB2DB ServerA ServerB ServerC Availability Groups Listener allow applications to failover seamlessly to any secondary; reconnecting through Virtual Network Name Connect to new primary once failover is complete and the listener is online

Availability Group uses WSFC for Database Active Log Synchronization Database Active Log Synchronization WSFC is a Common Microsoft Availability Platform

Note: More secondaries (total up to 4) can be added for additional resiliency or read scale out Primary Data Center Disaster Recovery Data Center Synchronous / Asynchronous PrimarySecondary Fileshare Witness Synchronous Secondary Availability Group

Multiple no data loss secondariesMultiple no data loss secondaries Better data loss protection for DR secondaries through continuous replication Faster failover to DR Faster failover to DR secondaries through virtual name failover Unified solution Simple deployment Unified dashboard Rich diagnosticsRich diagnostics Centralized management of client connection topology Multi-DB failoverMulti-DB failover New Management Dashboard

IT EFFICIENCY AND COST- EFFECTIVENESS ARE CRITICAL FOR BUSINESSES Idle hardware Idle hardware is no longer an option. ACTIVE SECONDARY USES Read-only Read-only workloads Offloading Offloading Backups Active Secondary AlwaysOn Active Secondary enables efficient utilization of high availability hardware resources to improve overall IT efficiency

SQLservr.exe offloading read queries to secondaryReadable secondary allow offloading read queries to secondary Low data latencyLow data latency automatically redirected After failover, the read applications can be automatically redirected to the new Secondary (require explicit connection request) replication scenariosNot a replacement for replication scenarios PrimarySecondaryPrimarySecondary Database Log Synchronization DB2DB1 InstanceB Reports DB2DB1 InstanceA Reports CRASH

SecondaryPrimary Log Cache Secondary read is always behind primary during transaction activity DB1 Log Log Capture Log Receive DB1 Data Redo Thread Redo Pages DB1 Log DB1 Data Log Hardened Log Flush Commit Acknowledge Commit Log Pool Log Capture

CONCURRENCY AND BLOCKING REDOREDO can get blocked by reporting workload REDOREDO thread and read workload can deadlock SOLUTION Internally map blocking isolation Internally map read workload to non blocking isolation levels (no application changes required) Read Uncommitted  Snapshot Isolation Read Committed  Snapshot Isolation Repeatable Read  Snapshot Isolation Serializable  Snapshot Isolation Ignore all locking hints REDONever choose REDO as deadlock victim PRIMARYSECONDARIES ReadRead/Write RESULT Blocking and deadlock between Reporting workload (i.e. Query) and REDO thread is eliminated No issues with DML (INSERT/DELETE/UPDATE) as it is not allowed Will incur additional cost of row versioning.

READ / WRITE WORKLOAD AG Listener Connecting using AG Listener Connection using FAILOVER_PARTNER (if connection string of existing applications can’t be changed) READ ONLY WORKLOAD ApplicationIntent=ReadOnly Connection using VNN and ApplicationIntent=ReadOnly Connection to the secondary instance directly ReadOnly Routing MULTI SUBNET FAILOVER SCENARIO: New client libraries => MultiSubnetFailover=True New client libraries => MultiSubnetFailover=True Old client libraries configure appropriate client connection timeout CLIENT PRIMARYSECONDARIES

Backups from any replica Synchronous or asynchronous secondaries Primary backups still work Adds capacity Adds capacity to primary server by off- loading backups to a replica Log backups done on all replicas form a single log chain Recovery Advisor makes restores simple RECOVERY ADVISOR

All SQL servers (including the secondary in the DR site) in the same Windows domain One Windows Server Failover Cluster spreads over the primary and DR sites All the databases must be in FULL recovery model unit of failover is at the AG level The unit of failover (for local HA, as well as DR) is at the AG level, i.e., group of databases – not the instance Consider using Contained Database for containing logins for failover For jobs and other objects outside the database, simple customization needed No delayed apply on the secondary like log shipping Removing log shipping means the regular log backup job is removed Need to re-establish periodic log backup (essential for truncating the log) AlwaysOn Dashboard System Center Operations Manager

High Availability Provide High Availability at the Instance Level Unit of failover = SQL server instance Maintain same virtual network name after failover. Clients re-connect to same name Instance restart requires database to go through recovery Disaster Recovery Provide Disaster Recovery at the Instance Level Provide Disaster Recovery protection from site failure: be it network, power, infrastructure or other site disasters. Require storage based replication technology and networking considerations Multi-subnet support: HA & DR Solution SQL Server 2008 R2 NO Create stretch Virtual-LAN (VLAN) to act as a single subnet SQL Server 2012SQL Server 2012 YES IP address OR dependency support IP address OR dependency support within SQL Server setup SQL Engine skips binding to IP’s not online on start-up

Corpnet Network Name: SqlClust subnet 1subnet 1subnet 2subnet 2 IP1: IP2: SAN Replication Local Site Remote Site OR

WHY WE ENABLE THIS? tempdb access occupies large % of SAN I/O Fast local HDD/SSD becomes standard Server configuration BENEFITS Better overall performance Cost saving IMPORTANT NOTE! Ensure that tempdb local paths are available to SQL Service on all the nodes LOCAL TEMP DB LOCAL TEMP DB (Fast disk, SSD) SECONDARIES PRIMARY

Diagnos tics Configurable options eliminate false failover Improved logging for better diagnostics

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