Using SQL Server 2012 AlwaysOn Availability Groups for failover of SharePoint 2010 Databases, as presented at the Australian SharePoint Conference - March 2012 in Melbourne.
3. What we will cover
SQL 2012 AlwaysOn
• What is SQL 2012 AlwaysOn?
– AlwaysOn Failover Clustering
– AlwaysOn Availability Groups
• Why AlwaysOn Availability Groups for SharePoint?
• Requirements and Prerequisites
• Step by Step guide to implementing AlwaysOn Availability
Groups
• Demonstration
4. SQL 2012 AlwaysOn
Hype or Reality?
• Two distinct technologies that share the same name
• AlwaysOn Failover Clustering is a different thing!
– A Failover Cluster Instance (FCI) uses traditional Shared
Storage Clustering (one copy of data shared by multiple
nodes)
– Same marketing name, but completely different
technology
• AlwaysOn Availability Groups correspond to the new version
of SQL Database Mirroring – High Availability and Disaster
Recovery at the Data Tier
5. History of AlwaysOn Availability Groups
Background and Predecessor Technologies
• Original concept was log shipping in SQL 2000 –
making a duplicate copy of your databases on another
server
• Mirroring itself introduced in SQL 2005 SP1, improved
in SQL 2008 and SQL 2008 R2
• Works by keeping a mirror copy of a database or
databases on up to four additional SQL instances.
• AlwaysOn Availability Groups introduced with SQL
2012, added up to four mirror copies, and more
• This is a huge change to data tier design for
SharePoint
6. Comparison of AlwaysOn with other SQL HA
Greatly Improved HA and DR
Potential Potential
High Availability and Disaster Recovery Automatic Readable
Data Loss Recovery
SQL Server Solution Failover Secondaries
(RPO) Time (RTO)
AlwaysOn Availability Group - synchronous-commit Zero Seconds Yes 0-2
AlwaysOn Availability Group - asynchronous-commit Seconds Minutes No 0-4
AlwaysOn Failover Cluster Instance NA Seconds Yes NA
-to-minutes
Database Mirroring - High-safety (sync + witness) Zero Seconds Yes NA
Database Mirroring - High-performance (async) Seconds Minutes No NA
Log Shipping Minutes Minutes No Not during
-to-hours a restore
Backup, Copy, Restore Hours Hours No Not during
-to-days a restore
7. AlwaysOn Availability Groups
Design Options
• Create up to four additional copies of each database
on a different SQL node
• Copies can be a mix of synchronous (exact copy) or
asynchronous (works across low latency link)
• Create a synchronous copy when connectivity is 1Gb
or greater and latency is no more than 10ms
• Create asynchronous copies across WAN links, for
Disaster Recovery or when architecting a read-only
farm
8. AlwaysOn Availability Groups
Read-only Farms
• Unlike SQL Mirroring, AlwaysOn Availability Groups
allow for read-only access to the content on a remote
SQL instance
• Allows for the DR copy of the data to be used as part
of a view-only SharePoint farm in a remote location
• Requires a separate SharePoint farm from the
production read/write farm
10. AlwaysOn Availability Groups for SharePoint
Improving Data Tier High Availability and Disaster Recovery
• Completely changes the design options for the data tier
• Allows for ‘Exchange Server’ like multi-copy database server failover
on multiple replicas at the same time
• The equivalent of running a constant backup of your databases
• Can be used to create HA/DR copies of your SharePoint databases
• SharePoint no longer needs to be ‘aware’ of the mirrored copy (in
fact, it won’t failover if you configure it manually in SPCA.)
SharePoint connects to the listener (Client Access Point) which is
clustered
• SharePoint 2010 Service Pack 1 supports SQL 2012 fully
CAVEAT: Be sure to understand that synchronous mirroring copies need
to be in close proximity and have very good bandwidth, as data needs to
be written into all replicas before the transaction is committed.
SharePoint will lock up if there are any interruptions at the data tier.
11. AlwaysOn Availability Groups
Version Requirements
• Windows Server 2008 R2 (w SP1 ideally, as patches
are required) – Enterprise Edition
– One per node
– Can use Virtualization licensing options
– Should also work on Windows 8 Server
• SQL Server 2012 Enterprise Edition
– MS has moved to ‘Oracle model’ of licensing, based
on CPU power
– Legacy licenses of SQL 2008/2005 Enterprise are
‘grandfathered in’ if you have upgrade assurance
12. AlwaysOn Availability Groups
Prerequisites and Requirements – Windows OS
• Cannot be installed on a Domain Controller
• Must be either x86 (non-WOW64) or x64 Windows
Server 2008 or later versions.
• Must be a node in a Windows Server Failover
Clustering (WSFC) cluster.
• Ensure that WSFC cluster contains sufficient nodes to
support your availability group configurations.
• Ensure that all applicable Window hotfixes have been
installed on every node in the WSFC cluster (Taken
care of with SP1 for Windows Server 2008 R2)
13. AlwaysOn Availability Groups
Prerequisites and Requirements – SQL Server
• If you plan to use a SQL Server failover cluster
instance (FCI) to host an availability replica, ensure
that you understand the FCI restrictions and that the
FCI requirements are met (Manual config required)
• All the server instances that host availability replicas
for an availability group must use the same SQL Server
collation.
• If any databases that use FILESTREAM will be added to
an availability group, ensure that FILESTREAM is
enabled on every server instance that will host an
availability replica for the availability group.
14. Creating AlwaysOn Availability Groups
Sample Setup used for the Presentation
• For this discussion and
demo, I created a three
node WSFC with
SQL1, SQL2, and SQL3
• SharePoint server SP1
connects to the listener
‘SQL’
• Failover is automatic
between SQL1 and SQL2
(Synchronous)
• Failover manual to SQL3
15. Creating AlwaysOn Availability Groups
Step 1: Create Windows Server Failover Cluster (WSFC)
• Install Windows Server 2008 R2
w/SP1 on multiple nodes
• Enable the Failover Cluster
Feature on each node
• Use the Failover Cluster Manager
Wizard to create a cluster.
• Name the cluster a unique name
that will be separate from the
instance name that will be used
for SharePoint
16. Creating AlwaysOn Availability Groups
Step 2: Prepare Nodes
• Install .NET Services 3.5 Feature on each SQL node
• Install SQL 2012 Enterprise Edition Database Services (Also recommend
adding SQL Management Tools – Complete)
• Ensure proper Windows Firewall ports are open
• Service Account for SQL
– Use the same service account for all nodes
– Don’t use Network Service
– If using Kerberos, make sure all SQL names have SPNs associated with
the service account
• Make sure databases are set to FULL recovery mode
• Ensure that the file paths and drive letters are consistent throughout all
instances (ideally, or config will have to be manual)
• Copy or Create SharePoint databases on Primary node only (use SQL Alias to
change name later)
• Perform a full backup of your SharePoint databases
• Create a file share location that is accessible by all nodes that will be used
for the shared backups (i.e. SQL1Backups)
17. Creating AlwaysOn Availability Groups
Step 2: Enable AlwaysOn on each SQL Node
• Enable AlwaysOn High
Availability in SQL Server
Configuration Manager
• Repeat on Each Node
• Restart SQL Services
18. Creating AlwaysOn Availability Groups
Step 3: Create the Availability Group
• Ideally use the New Availability Group
Wizard, it automates the process
19. Creating AlwaysOn Availability Groups
Step 3: Create the Availability Group – Continued…
• Be sure to have a
shared network
location for the
backup files
(Created in earlier
step)
• Depending on size of
databases, this
could take a while
• Backups can also be
pre-staged (Join
Only)
20. Creating AlwaysOn Availability Groups
Step 3: Create the Availability Group – Continued…
• Validation should
show all
green, except
warning for
Listener
• The listener (‘SQL’
in this example)
will be created
later, and is
required for
SharePoint to
connect to
21. Creating AlwaysOn Availability Groups
Step 4: Create the Availability Group Listener
• After the wizard
completes, manually
create the Availability
Group Listener
• This is the shared
name that SharePoint
will connect to and will
provide failover (Also
called the ‘Client
Access Point’)
• Modify the DNS record
for this listener to have
a low TTL (60 seconds
or less) for cross-
subnet failover
scenarios
23. Session Summary
• Throw away all previous data tier designs for
SharePoint!
• SQL 2012 AlwaysOn Availability Groups are the
preferred design option for High Availability and
Disaster Recovery at the data tier
• SQL 2012 is fully supported by SharePoint 2010
Service Pack 1 databases
• Follow closely the guidelines, ensure data paths are
the same, double-check security requirements