1. SQLSaturday (Silicon Valley) – Mar 03 2012
SQL Server AlwaysON – Next gen HADR solution
SQLSaturday (Silicon Valley) – Mar
Prakash Heda

2. Email/Facebook: Prakash@SQLfeatures.com MCDBA/MCITP
Prakash Heda
Senior Infrastructure DBA at Advent Software
Blog:
/Facebook: MCDBA/MCITP

3. Agenda What is SQL Server AlwaysOn AlwaysON failover cluster Instance
What is AlwaysOn Availability Group
Availability group on failover cluster Instance
SQL 2012 HA comparisons
Multiple Active Secondary
AlwaysON Live configuration DEMO
Conclusion

4. What is SQL Server AlwaysOn
It’s like mirroring, with multiple mirrors where databases can fail over in groups, and shed load by querying the mirrors, offloading backups.
Windows Server Failover Cluster
AlwaysOn Availability Groups
for database protection
AlwaysOn Failover Cluster Instances
for instance level protection
Availability Group uses Windows Server Failover Cluster (WSFC) for
Inter-node health detection,
Failover coordination,
Primary health detection,
Distributed data store for settings and state,
Distributed change notifications
WSFC to perform Witness role
Support for Windows Server Core
Reduce OS patching by as much as 50-60%
Support for rolling upgrade and patching of SQL Server for both Availability Groups and Failover Cluster Instance
Fast failover time for both Availability Groups and Failover Cluster Instances
New online operations supported
LOB Index
Adding of column with default

5. AlwaysOn failover cluster Instance
Key Enhancements
Windows Server Core
Multi-site clustering across subnets
Support for tempdb on local drive
Flexible Failover Policy
Improved system diagnostics
Fast instance failover through predictable database recovery time
Automatic dns propogation

6. AlwaysOn Availability Groups
AlwaysOn Availability Groups is a new feature that enhances and combines database mirroring and log shipping capabilities
Flexible
Integrated
Efficient
Multi-database failover
Multiple secondaries
Total of 4 secondaries
2 synchronous secondaries
1 automatic failover pair
Synchronous and asynchronous data movement
Built in compression and encryption
Automatic and manual failover
Automatic Page Repair
Local storage
Application failover using virtual name
Configuration Wizard
Dashboard
System Center Integration
Rich diagnostic infrastructure
File-stream replication
Replication publisher failover
Supports Contained databases
Active Secondary
Readable Secondary
Backup from Secondary
Automation using power-shell
However, it is still configured on a "per database" level so you are not replicating the entire SQL instance.  It also has the same restrictions as Database Mirroring in terms of support of databases that use distributed

7. SQL Server 2012 AlwaysON Comparison
Test scenario AlwaysON Failure Mitigation AlwaysON Performance Improvements & Load Balancing
In this series of Videos will use Hyper-V to evaluate 2012 AlwaysOn HADR feature for 2 node cluster
Part 1: Network Configuration for 2 node cluster
Part 2: Setup Domain Controller
Part 3: Add Storage Server to Domain Controller
Part 4: Preparing nodes for failover cluster
Part 5: Configure 2 node failover cluster
Part 6: Install Standalone 2012 on both nodes
Part 7: Enable availability Groups
Part 8: Configure Availability Groups with 2 DB’s
Part 9: Readable replica & test force failover
Part 10: Implement & Test Virtual Name
2012 CTP1 windows 2008 R2 HyperV AlwaysON AvailablityGroup

8. HA Test scenario Automated failover No single point of failure
Zero data loss
Separate server for reporting
DR site with 5 min of Data loss acceptable

9. SQL Server 2008 R2 HADR Solution
Log Shipping
Async
Sync
Site 1
Secondary Mirror
Active Node/ Primary Mirror Q F G
Shared Storage
W S F C Cluster
Passive Node
Log Shipping 2
Site 2
Maintenance effort
Connection drop-off on reporting server
DB snapshot
Manual logshipping

10. SQL Server AlwaysON HADR Solution
Site 3
File Share Witness
W S F C Cluster
Secondary 1
Async
Sync
Secondary 2
Site 2
Secondary 3
Primary Mirror Q F G
SAN Storage
Manual Failover
Maintenance effort
Connection drop-off on reporting server
DB snapshot
Manual logshipping
Automatic Failover 1
Site 1
Manual Failover

11. SQL Server AlwaysON HADR Solution
Site 3
File Share Witness
W S F C Cluster
Secondary 1
Async
Sync
Secondary 2
Manual Failover
Manual Failover
Virtual Name
Site 2
Secondary 3
Primary Mirror Q F G
SAN Storage
Manual Failover
Maintenance effort
Connection drop-off on reporting server
DB snapshot
Manual logshipping
Automatic Failover 1
Automatic Failover 1
Site 1
Manual Failover

12. Availability Group Scenario Multiple Secondary's
Windows Server Failover Cluster
Node A
Node B
Secondary
AG2
AG1
Secondary
AG4
Node C
Node D
Secondary
Secondary
Secondary
AG3

13. Client Failover with Virtual Name
SQL Server Name : qdcdb21 & 22 & 23
Virtual Name: qdcVsql
Availability Group Name qdcAG
Synchronous Mirroring
App Layer
Write Transaction
Write Transaction
Read Transaction
qdcAG
qdcVsql
DB1
DB2
qdcdb22
DB1
DB2
qdcdb21
DB1
DB2
qdcdb23
Auto Failover
W S F C Cluster

14. AlwaysON Failure Mitigation
Attribute
Clustering
Log shipping
Database mirroring
Availability group
Failure detection
Yes No
Automatic failover
Perceived downtime
30 seconds + recovery
N/A
3 seconds
Less than 3 seconds (per database)
Potential data loss
All databases
Latest transaction logs
No Loss
No Loss/ Multiple Copies
Masking of storage failure
No – shared disk
Yes (Multiple copies)
Failover level
Instance
Each database
Group of databases (multiple)
Scope
System and user databases
User databases
Virtual Name
Yes (One per instance)
Failover Partner
Yes (One for every group)
Multi Site Auto Failover
Multi Subnet

15. AlwaysONPerformance Improvements & Load Balancing
Attribute
Clustering
Log shipping
Database mirroring
AlwaysON
Readable Secondary No
Yes
Yes (only snapshots, stale data)
Connection Loss NA
Yes (Redo logs)
Backup from Secondary
Deployment & maintenance
Medium
Difficult
Easy
Flexible failover policy
DBCC on secondary
Yes(Only read operation)
Patch Upgrade downtime
Minimum
Statistics on reporting node
Multiple database Copy
One set
Multiple sets
Two sets
Up to 5 Sets

16. AlwaysOn Active Secondary
IT efficiency and cost-effectiveness
Idle hardware is not an option anymore
Balancing read-only workloads
Offloading Backup Operations
Generate statistics on tempdb
Can run dbcc commands
Log backup on any replica

17. Database Mirroring Basic Principal of Synchronous Mirroring
Acknowledge
Commit
Acknowledge
Constantly Redoing on Mirror
Transmit to Mirror
Write to Local Log
Committed in Log
Log Harden DB
Log
Log DB

18. Readable Secondary Behavior
Contention between redo thread and query thread avoided by
Internally mapping read workload to non blocking isolation levels
Read Uncommitted  Snapshot Isolation
Read Committed  Snapshot Isolation
Repeatable Read  Snapshot Isolation
Serializable  Snapshot Isolation
Ignore all locking hints
Maintains query performance on secondary compared to primary
Auto-create statistics on the secondary replica but persist them in TempDB
Will incur additional cost of row versioning

19. Read-Only Client Connectivity
New connection string options
ApplicationIntent
Read-Only Automatic Routing
MultiSubnetFailover
Driver Support in RC0
MultiSubnetFailover=True Not Supported by NET Framework or OLEDB
In RC0, only SQL Native Client 11.0 ODBC supports MultiSubnetFailover=True.
Read-Only Routing enables redirection of client connection to new secondary on role change
Driver
Multi-Subnet Failover
ApplicationIntent
Read-Only Routing
SQL Native Client 11.0 ODBC
Yes
SQL Native Client 11.0 OLEDB No
ADO.NET with .NET Framework 4.0
Q4 CY2011*
Q4 CY2011
Microsoft JDBC driver 4.0 for SQL Server

20. Active Secondary – Making Secondary Readable
Failover
SQLservr.exe
SQLservr.exe
Primary
Secondary
Secondary
Primary
InstanceA
InstanceB
DB2
DB1
DB2
DB1
Reports
Reports
Readable secondary allow offloading read queries to secondary Close to real-time data, latency of log synchronization impact data freshness

21. Active Secondary: Enabling Backup On Secondary
Backups can be done on any replica of a database Backups on primary replica still works Log backups done on all replicas form a single log chain Differential backups are not supported on secondary Only Copy-only full backups are supported on secondary

22. Multi-Site Clustering
Multi-site clustering provides protection from site failures
DNS Server
Network name DNS
record created
Network name DNS record created
Network name DNS record Updated
Node 1
Node 2
Node 3
Node 4
Failover
At any given time, one out of two IP address will always be offline. By default SQL VNN creation will register all IP addresses in DNS (RegisterAllProvidersIP=1) which means all clients trying to connect via VNN will have multiple IP addresses registered in cache, in my case there were two. This is helpful specially in failover scenarios where clients can seamlessly connect to new primary without waiting for DNS propagation to complete
Set RegisterAllProvidersIP=0 and HostRecordTTL=30 so only online IP is registered in DNS and upon failover maximum wait for client to know about new updated IP addresses will  be 30 seconds.
Increase the connection timeout on clients to 30+ seconds.
Use "multisubnetfailover=true" in client connection string. In CTP 3 this feature is limited to SQL Native client and those who are using ADO.Net have to wait till this parameters gets back ported into next release of .Net framework, which will not happen till October
Site A
Site B
Data Replication
AlwaysOn Failover Cluster Instance natively supports multi-site clustering without requiring V-LAN
Each site can have separate IP subnet
DNS entry updated to reflect current IP address on failover

23. Contained Databases Introducing Contained Databases or CDB’s
Unit of application programmability in 2012
A DB which establishes a boundary between application and server
CDBs sever the user–login relationship
Windows users no longer need matching logins
Users with passwords replace SQL logins
CDB can be part of an availability group and can failover across replicas Authentication information moves with the CDB Limitation Other objects, like jobs are not contained and has to be managed
Windows 2008 R2 Core support
Less patches, more secure, powershell support
Steps:
Use for standard VM with minimum configuration
Sysprep Pre-Image standalone SQL Server configuration
Powershell installation, graphical interface in RTM

24. Introducing Flexible Failover Policy
Flexible Failover Policy provides administrators control over the conditions when an automatic failover should be initiated.
SQL Server 2012
Resource DLL
SQL Server
sp_server_diagnostics
Diagnostics
Resource DLL
SQL Server
Select
SQL Server 2008 R2
Configurable options eliminate false failover
Improved logging for better diagnostics

25. AlwaysOn Setup with RC0 Windows Server 2008 R2 SP1
Install WSFC on each machine and create a single WSFC cluster
Install Standalone/Cluster SQL Server Instances on each machine
Enable AlwaysOn through SQL Configuration Manager
Configure availability group
Optional Shared storage
Enable TCP/IP
No Heartbeat network
Full Recovery model
Database Backup
Windows Authentication

26. Demo Videos (SQL 2012 Configuration)
Part 1: 2012 setup & Network Configuration Part 2: Configure Windows 2008 R2 Domain Controller Part 3: Preparing nodes for failover cluster Part 4: Configure 2 node Windows 2008 R2 SP1 failover cluster Part 5: Install Standalone 2012 on both nodes Part 6: 2012 Availability Groups Explained (Session 1) Part 6: 2012 Availability Groups Explained (Session 2) Part 6: Enable availability Groups (Session 3) Part 7: Configure Availability Groups with 2 DB’s Part 8: Readable replica & test force failover Part 9: Implement & Test Virtual Name
In this series of Videos will use Hyper-V to evaluate 2012 AlwaysOn HADR feature for 2 node cluster
Part 1: Network Configuration for 2 node cluster
Part 2: Setup Domain Controller
Part 3: Add Storage Server to Domain Controller
Part 4: Preparing nodes for failover cluster
Part 5: Configure 2 node failover cluster
Part 6: Install Standalone 2012 on both nodes
Part 7: Enable availability Groups
Part 8: Configure Availability Groups with 2 DB’s
Part 9: Readable replica & test force failover
Part 10: Implement & Test Virtual Name
2012 CTP1 windows 2008 R2 HyperV AlwaysON AvailablityGroup

27. Demo Setup (Windows 2008 R2 SP1)
VM1
VM2
VM3
System Name
W2k8R2dc
Qdcdb21
qdcdb22
OS detail
W2k8R2 SP1
As DC/DNS (NO DHCP) & Storage Server
W2k8R2 SP1 Node1
W2k8R2 SP1 Node2
IP/Subnet/DNS
Domain NIC
/ /
/ /
/ /
ClusterVIP/Name
/alwaysonCls
Virtual Name VIP
Domain\User
sqlfeatures.local\cls
Availability Group
AlwaysONavg
DEMO

28. Useful Links for evaluation RC0
SQL Server 2012 RC0 is now public
TechNet 180 day evaluation copy of Windows Server 2008 R2 Sp1
Step-by-step guide on my blog:

29. Thank You SQLSaturday (Silicon Valley) – Mar 03 2012
Blog:
Thank You
For Attending this session
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