Thursday, March 19, 2015

Things to Remember during SQL SERVER HA Configuration

Recently configured a SQL SERVER high availability Cluster in AWS. the process was smooth and i followed a provided documentation however things to remember when configure HA in AWS

  1. Make sure your Cluster Quorum is on a separate host within different security zone just to ensure you fail-overs are remain intact in case of node failure.
  2. Each HA cluster need entries in primary DNS server to ensure parallel requests are processed however normal TTL time is 300 which means secondary server will not be available till 5 minutes of the last fail-over this situation can create real confusion during testing and configurations. so keep that minimum
  3. make sure your nodes are joined with this will help to use single user and permission level across all machines.
  4. the stuff i forgot during deployment was the binding of multiple IP address to the private network subnet. if the setting is not there listener will unable to communicate from the network locations.
  5. make sure your port 1433 is open from all security zone and port 137 and 139 are open from quorum witness.
  6. Opens the TCP ports 1433, 1434, 4022, 5022, and 135 on the Windows Firewall
  7. for cluster node need to ensure that static IP option is selected by default its dynamic. in case of dynamic IPs your cluster will remain offline.
  8. Ensure required Database is uses Full Recover model.
    1. SELECT name, recovery_model_desc  FROM sys.databases
  9.  Check DNS to ensure all availability group Listeners (e.g., AG1-Listener) IP addresses are listed.

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