I have verified all our SQL Servers and created attached document to track the migration activity.

Please find the below high level migration plan.

1. Checking the SQL Server Version and edition 

2. Checking the OS version 

2. Pickup the servers that are going to EOL soon

Migration plan : Prefered target version of SQL Server is SQL Server 2017

1. check the application compatability for sql server 2017

2. if application is compatable start the new server build with the same configurations as source for always on servers

3. We have cluster server with OS Window Server 2016, Hence we can do the In-Place upgrade for SQL Server to 2019 for cluster servers.

Plan for Always ON servers :

1. Build the new VMs with same configurations as source

2. Add the VMs into cluster and configure the cluster

3. Configure the Always ON

4. Migrate all the databases and related objects(jobs, logins, linked servers, ssis packages) during the cutover time.

Plan for Failover cluster servers:

1.Current OS version for all failover clusters is Windows server 2016

2.Perform the In-Place upgrade from SQL Server 2014 to SQL Server 2017

Detailed migration plan along with teh migration checklist will be shared after we agree on the above plan.

I'm planning to pick the 'xxxx' server first as it is going to EOL soon.

ADD and Remove the DB from AG

 

Removing the DB from AG group:

 

1.       Connect to the server 'Server Name' using SSMS

2.       Click On Availability Groups and expand the Availability groups and expand Availability databases

 

3.       Now right click on the selected database and click on remove database from availability Group

 

4.       Now notice the database has been removed from the availability group

 

Re adding the DB to AG group :

 

1.       Connect to the secondary node 'Server Name '

2.       Notice the database that we removed from AG is in restoring state

3.       Drop the database from the secondary node

Drop database 'DBname'

4.       Connect to the Primary Node again

5.       Go to Availability Groups and expand AG Group and expand availability databases

6.       Now right click on availability databases and click on

 

7.       Now select your database to add to AG in the window and click next

 

 

8.       Now click on connect to connect secondary replica and click next

 

 

9.       Now select the second option and give the shared path as shown in below image and click next

 

 

10.   Now click on Next--> Next---> Finish

11.   Notice the database is added to the AG group and it is in synchronised state