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What is readable secondary replica?
Readable secondary: No – It does not allow any user connections for the secondary replica. It is the default configuration. We can change the Readable secondary to the following values. Read-intent only: In this mode, the secondary database allows the read-only connections. Users with the appropriate access can read …
How many secondary replicas are supported by an AlwaysOn availability group?
eight secondary replicas
Up to eight secondary replicas are supported, including one primary replica and two synchronous-commit secondary replicas.
How many secondary replicas are there in SQL Server 2016?
8 secondary replicas
Up to 8 secondary replicas, including 2 synchronous secondary replicas (SQL Server 2016) Up to 8 secondary replicas, including 2 synchronous secondary replicas (SQL Server 2017) Up to 8 secondary replicas, including 5 synchronous secondary replicas (SQL Server 2019)
What is the difference between configuring the secondary replica as readable or read-intent only?
The Secondary role has a new value from the readable secondary drop list. This option allows reading access of the secondary databases of this replica. Only read-only connections are allowed. This option allows to read access only but all the connections are allowed for the secondary replica.
What is the maximum number of secondary replicas we can configure in a SQL Server 2016 AlwaysOn availability group?
Each availability group supports one primary replica and up to eight secondary replicas. For more information, see Overview of Always On Availability Groups (SQL Server).
How do you implement high availability?
Here are some of the key resources you can implement to make high availability possible:
- Implement multiple application servers.
- Scaling and slaves matters.
- Spread out physically.
- Maintain a recurring online backup system along with hardware.
- Use of a virtualized server for zero-downtime recovery.
What does it mean to have a readable secondary replica?
A readable secondary replica can be in either synchronous-commit availability mode, or asynchronous-commit availability mode. A readable secondary replica allows read-only access to all its secondary databases. However, readable secondary databases are not set to read-only.
Why is readable replica not fully supported in SQL Server?
Some operations are not fully supported, as follows: As soon as a readable replica is enabled for read, it can start accepting connections to its secondary databases. However, if any active transactions exist on a primary database, the row versions will not be fully available on the corresponding secondary database.
Can a secondary replica remain online when the primary replica is offline?
Beginning in SQL Server 2014 (12.x), readable secondary replicas can remain online even when the primary replica is offline due to user action or a failure, for example, synchronization was suspended due to a user command or a failure, or a replica is resolving status due to the WSFC being offline.
How to enable read-only access to secondary availability group replica?
A stand-alone server instance, COMPUTER03\\HADR_INSTANCE, is specified to host the new availability replica. This replica configured to allow only read-write connections for the primary role and to allow only read-intent connections for secondary role.