Server A is configured with AlwaysOn (2/3 nodes) and holding 40TB of data in Azure. Want to create a similar instance as Server B with AlwaysOn configured. Client is not willing to provide downtime more than 30 minutes

Question

Server A is configured with AlwaysOn (2/3 nodes) and holding 40TB of data in Azure. Want to create a similar instance as Server B with AlwaysOn configured. Client is not willing to provide downtime more than 30 minutes

Chatterjee, Somnath [Non-PG] 25

Hello,

I have a server (Server A) configured with AlwaysOn (2/3 nodes) and holding 40TB of data in Azure. I need to create a similar instance (Server B) with AlwaysOn configured in a different Azure tenant. The client is not willing to provide downtime of more than 30 minutes.

The setup is on IaaS, and the migration is from one Azure tenant to another Azure tenant. Could you please provide guidance on the best approach to achieve this with minimal downtime?

Thank you!

Vijayalaxmi Kattimani 2,985 Reputation points Microsoft External Staff Moderator

2025-05-12T11:08:18.17+00:00
Hi Chatterjee, Somnath [Non-PG]

Greetings!

As we understand that, you are looking to create a new AlwaysOn instance (Server B) with minimal downtime while migrating from Server A in a different Azure tenant. Since you have got 40TB of data and only a 30-minute downtime window, here are a few strategies to consider:

Always On Availability Group: Since Server A is running on AlwaysOn, you might want to set up an AlwaysOn Availability Group for Server B in the new tenant. You can create the new database setup while keeping Server A active.

During the migration:

Set up a secondary replica in Server B and configure the databases for replication.

After the initial synchronization is complete, you can perform a final synchronization followed by a planned failover. This usually allows for minimal downtime as the main database remains available during the process.

Consider Load Balancing: If you can load balance traffic between the two servers during the migration, this would help manage the transition smoothly and reduce user impact.

Use Data Sync: If you're not tied specifically to AlwaysOn, you may explore using Azure SQL Data Sync to replicate data from Server A to Server B, although this may involve more complexity regarding transaction consistency.

Plan in Off-Peak Hours: Regardless of the method, ensure that you plan this migration during off-peak hours to further minimize the impact.

I hope this information helps. Please do let us know if you have any further queries.
Vijayalaxmi Kattimani 2,985 Reputation points Microsoft External Staff Moderator

2025-05-13T09:24:51.5333333+00:00

Hi Chatterjee, Somnath [Non-PG]

We haven’t heard from you on the last response and wanted to follow up to check if your issue has been resolved.

If you have found a solution, we would appreciate it if you could share it with the community, as it may be helpful to others. Otherwise, please provide more details, and we will do our best to assist you further.
Vijayalaxmi Kattimani 2,985 Reputation points Microsoft External Staff Moderator

2025-05-14T09:10:17.64+00:00

Hi Chatterjee, Somnath [Non-PG]

We haven’t heard from you on the last response and wanted to follow up to check if your issue has been resolved.

If you have found a solution, we would appreciate it if you could share it with the community, as it may be helpful to others. Otherwise, please provide more details, and we will do our best to assist you further.

1 answer

Your answer

Vijayalaxmi Kattimani 2,985 Reputation points Microsoft External Staff Moderator

2025-05-12T11:08:18.17+00:00

Hi Chatterjee, Somnath [Non-PG]

Greetings!

As we understand that, you are looking to create a new AlwaysOn instance (Server B) with minimal downtime while migrating from Server A in a different Azure tenant. Since you have got 40TB of data and only a 30-minute downtime window, here are a few strategies to consider:

Always On Availability Group: Since Server A is running on AlwaysOn, you might want to set up an AlwaysOn Availability Group for Server B in the new tenant. You can create the new database setup while keeping Server A active.

During the migration:

Set up a secondary replica in Server B and configure the databases for replication.

After the initial synchronization is complete, you can perform a final synchronization followed by a planned failover. This usually allows for minimal downtime as the main database remains available during the process.

Consider Load Balancing: If you can load balance traffic between the two servers during the migration, this would help manage the transition smoothly and reduce user impact.

Use Data Sync: If you're not tied specifically to AlwaysOn, you may explore using Azure SQL Data Sync to replicate data from Server A to Server B, although this may involve more complexity regarding transaction consistency.

Plan in Off-Peak Hours: Regardless of the method, ensure that you plan this migration during off-peak hours to further minimize the impact.

I hope this information helps. Please do let us know if you have any further queries.
Vijayalaxmi Kattimani 2,985 Reputation points Microsoft External Staff Moderator

2025-05-13T09:24:51.5333333+00:00

Hi Chatterjee, Somnath [Non-PG]

We haven’t heard from you on the last response and wanted to follow up to check if your issue has been resolved.

If you have found a solution, we would appreciate it if you could share it with the community, as it may be helpful to others. Otherwise, please provide more details, and we will do our best to assist you further.
Vijayalaxmi Kattimani 2,985 Reputation points Microsoft External Staff Moderator

2025-05-14T09:10:17.64+00:00

Hi Chatterjee, Somnath [Non-PG]

We haven’t heard from you on the last response and wanted to follow up to check if your issue has been resolved.

If you have found a solution, we would appreciate it if you could share it with the community, as it may be helpful to others. Otherwise, please provide more details, and we will do our best to assist you further.

Answer 1

Erland Sommarskog 121.3K MVP Volunteer Moderator

I will have to assume that you with Always On mean "Availability group". (Always On is an umbrella name, which besides AG also includes Failover Cluster Instances.)

One idea is to set up a distributed AG with the servers in the new AG in the other group. Once they have been seeded, you can fail over to the new AG. I believe that you should be able to remove the initial AG once you are done.

Share via

Server A is configured with AlwaysOn (2/3 nodes) and holding 40TB of data in Azure. Want to create a similar instance as Server B with AlwaysOn configured. Client is not willing to provide downtime more than 30 minutes

1 answer

Your answer