HANA system replication: will using hdbnsutil change parameter in both systems?

[Former Member]

Hello,

I know that one of the prerequisites for system replication scenario is to have identical .ini files in  both primary and secondary systems and the enable_fullsync parameter must be altered only using hdbnsutil.

In case I run hdbnsutil -sr_fullsync --enable on the primary system, will it change the parameter on the secondary system as well or do I do i have to go and do the same in the secondary system?

Thanks!

[Former Member · Accepted solution]

Hi Shimgaeva,

Change the parameters manually on secondary system.

Cheers

Sharma

[Former Member]

Thank you Gunda and Shrama!

Also while we are at system replication topic - just to clarify that I am getting it right:

If we need to register a secondary system, it must be down (mandatory) while the primary is up

In the case of takeover both of our system can be up and running and the secondary can takeover the primary or the primary can be down and the secondary can takeover.

Am I right?

[Former Member]

You are correct.

Additional Insight..when you perform the takeover

Make sure primary on Site A is completely stopped

Unbind virtual IP addresses (or change DNS entry)

On site B, run siteB # hdbnsutil -sr_takeover

Bind virtual IP addresses

Make sure backup is running on new primary

Regards,

Pavan Gunda

[Former Member]

wait, you are saying that when performing takeover the primary system MUST be stopped?

This is a video from SAP HANA Academy where he is showing Near Zero Downtime system upgrade using system replication scenario. It looks like both systems are up when he is performing the takeover...

SAP HANA Academy - System Replication: Near Zero Downtime Upgrade [SPS 09] - YouTube

[Former Member]

oops...Let me make it clear.

You can perform the takeover in both the ways.

1. In terms of real disaster --- > Here you primary will be completely lost. Then you can perform the take over. Then repair the Primary.

2. For DR Test (like upgrades,testings) --- > Here you can keep primary on and perform the take over.

Either of the way is correct. But, you need to stop your Primary either before takeover or after takeover to unbind the VIPS

The additional insight that i have mentioned is not mandatory. But the practice that i have followed.

Hope it is clear

[Former Member]

Ok that helps!

Found this in the Administration Guide as well. They do use "should" and not "must"

[Former Member]

You need to manually change the parameters in the secondary system. I see only data is getting synchronized but not the parmaters