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This blog gives you information about the minimal setup required for HANA high Availability. How to add standby host and perform a failover (simulation). How services, hosts and Volumes looks like before and after failover.

For high availability, a distributed HANA (scale out) setup is required.

The minimal setup for a scale out is 2 servers (one worker, one standby).

When an active (worker) host fails, a standby host automatically takes its place.

For that, standby host needs shared access to the database volumes.

Note: standby hosts do not contain any data and do not accept

requests or queries.

 

Host 1 (first node):

host role = Worker

host name = hanasl12

SID = HIA

Instance Number = 00

IP Address = 192.168.1.149

Host 2 (second node):

host role = Standby

hostname = hanadb4 (alias hanadb2)

SID = HIA

Instance number = 00

IP Address = 192.168.1.172

failover group = default

 

NFS is used here to shared file systems (/hana/shared, /hana/data/ and /hana/log)

export /hana from first node: /etc/exports

On second node: maintain /etc/fstab as shown below and mount the file systems.

Install SID= HIA, master node (first node) using installation media’s HDBLCM (the below screen shows services before adding standby node)

Hosts:

On master node: execute action configure_internal_network (using resident HDBLCM)

Then, on second node: run resident HDBLCM to add_hosts

Select Host role as “standby”

The below screen, shows services after adding standby node

Hosts – after adding standby node:

Volumes: (before failover) attached to active (worker) – on first node

To perform failover (simulation), I’ve killed deamon process

The below screen shows, stopped first node and now second node has Master name server (actual role) and Master Index server (actual role)

Volumes: (After failover) attached to second node

start instance on first node, it retains standby role (as actual role).

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