AlwaysOnIn SQL Server 2012

Fadi Abdulwahab – SharePoint Administrator - 4/2013

http://blogs.msdn.com/b/fabdulwahab/

Terminologies

High Availability (Planned and Unplanned)

Disaster Recovery

Recovery Time Objective (RTO)

Recovery Point Objective (RPO)

Budget

Solutions in SQL Server

Backup and Restore

Log Shipping

Replication

Mirroring

SQL Cluster

AlwaysOn

Mix and Third parties

Backup and Restore

Can lose data

Inexpensive Solution for DR

No HA

Log Shipping

HA , DR

No Automatic Failover but automate the process of backup and restore

Database Level

Inexpensive solution

Log Shipping

Replication

Database , Object level

No automatic failover

Can use as Load balance

HA , DR

Replication

Mirroring

HA , DR

Automatic failover (need witness server – optional)

Read-only database for secondary

Mirroring

SQL Cluster

HA

Expensive solution ( HD , License ,..)

Server level

Include two nodes or more

Required SAN Storage

A/P , A/A ,A/A/P,…

Need DR (Log shipping , Backup and Restore,..)

No Load Balance ( Use Transactional Replication)

SQL Cluster

AlwaysOn

New Feature in SQL Server 2012

Can have 5 replicas (one Primary and four secondary servers)

HA , DR (enhancement for mirroring) and Read-only access

Can be sync and async ( No acknowledgement ,minimize the transactions)

No need for SAN storage (Not like SQL Cluster)

Can deploy geographical

Can use Secondary servers for backup and reporting access

Automatic failover

Types (Primary (R/W and send trans logs to secondary) and Secondary (R)

AlwaysOn

Windows Cluster is required

Interchangeable ( Transactions terminated)

Failover can be ( Automatic , Manual and forced (possible data lose in case of async) (by commands)

Support T-SQL and PowerShell

Diff Backup not supported for secondary

Secondary use snapshots to avoid any blocking

Support page repair

Client can connect direct , Ava group and Read-only routing

Read-only settings ( No , Read –intent only , Yes)

Database should be :

Not belong to any Ava. Group

Enable R/W

Enable Multi User mode

Full Recovery

Full backup

Not used by mirroring

Automatic Failover (up to 2) (Required Sync)

Sync (Up to 3)

Need DNS and Static IP ( can be DHCP)

Configuration (Full (same path – need backup ) – Join (Already restored) – skip (restore later

When SQL user added to Primary the user must created in secondary (except if use contained databases – New feature in SQL Server 2012)

Backup Options

Prefer (run on secondary except if primary not online)

Secondary only (Not support diff backup)

Primary only (support diff backup)

Any replica (based on factors)

Demo

Prerequisites ( Windows Cluster , 2 instances at least)

Configuration (Enable , Create Ava. Group and backup)

Add/Remove databases …

Add/Remove Replica…

Suspended and resume…

Dashboard and DMVs for monitoring

Q&A

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