Its been a while I am doing Migration scoping and planning
along with Cloud implementation designing and deployment. While performing
migrations the important and crucial part is the cut-over so here I consolidated
steps for Cut-over.
Scenario := what I assumed here is Web servers running on the
VMware or on-prem and we have to migrate machines to Azure or any other cloud.
Using ASR or any block or image level replication tool like RiverMeadow etc.
Design – As per my scenario we are keeping the existing Domain
and migrating application and DB’s on Cloud. Below are Steps you need to keep in consideration -
- Extended the Domain to the Azure VM.
- Set
up the Replication infrastructure like for ASR we deploy Config server or
Master target server and incase of other Tools like RiverMeadow we deploy
Cloud appliance. This step is depend what tool are you using to perform
replication.
- Replicate
the VMs to the Cloud and using NSG to stop the communication with AD.
- Once
Replicated – Changed the name and remove from the domain.
- Restart
the VM and add to the Domain after allowing communication to the AD.
- For
DB – I assume we are using the PaaS SQL and used DMA for migration.
- Now
once everything is migrated to Azure or we call it Initial Sync then We
provide infrastructure to Customer for modification on IIS or any other
configuration as Ips going to change etc .
- Once
we have the go ahead we will plan for the Cut-Over.
Cut-Over : This is the Time where we would divert the
application URL to point to the Azure VM rather on-prem and Shutdown the
On-prem once Test is successful.
- As
soon as initial sync is done and all are configured on Azure VM. Infrastructure
is provided to the customer.
- Customer
then tests the applications, accessing the servers from those public IPs.
- Once
tested, We get the go ahead for the Cut-over Date and time.
- Customer
lowers the DNS TTL for the public domain names to 5 minutes. This happens
one day prior to cutover.
- At
cutover time, Differential needs to run and Testing needs to perform again
(Downtime). Once tested.
- Customers
changes the DNS records for the public domain names to resolve to the
public IP addresses of the new servers.
- Customer
retests the applications.
- Once
tested, We will open the firewall on port 443 to each of the new public
IPs, allowing access from all addresses. As for now only testers allowed to
access application over 443.
Now once all start working as expected – there are few steps
needs to wrap up the task.
Moves the FSMO roles
to the Azure VM holding windows AD.
Removes the AD role
and shut-down the VM and other on-prem servers gracefully.
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