April 2013 SQL Free Resource

15/4/2013
Microsoft TechEd India 2013

All presentations and video recordings of Microsoft TechEd 2013 are now available for viewing and download  here https://india.msteched.com/#agenda

SQL 2012 AG Failover and Failover Modes

Read this from Microsoft MSDN, and it make me understand how properties of failover modes affect AG failover

SQL 2012 AG Failover and Failover Modes

SQL AG - Availability Mode

I always ask myself why we need set synchronous /asynchronous mode in both primary and secondary group and what happen if synchronous set and secondary down? what will happen to primary.

Today get this answer:
If Primary server Availability mode = asynchronous
- Primary server will no wait for any secondary harden the log and it will commit immediately.
- The secondary will commit asynchronous no matter what mode you're configure on the AG mode in secondary

If Primary server Availability Mode = synchronous,
- Primary server will wait for transaction write into secondary server with AG mode=synchronous before being written to the local log file
- If secondary with synchronous timeout, Primary replica temporarily shifts into asynchronous-commit mode for that secondary replica. When the secondary replica reconnects with the primary replica, they resume synchronous-commit mode


Reference :
Availability Modes