Migrate vCenter Server 5.5 Windows to 6.0 Virtual Appliance 

Virtual appliance is future of how VMware delivery their product to customers. It’s pain to migrate from vCenter Server Windows version to virtual appliance. The only way was build up new virtual appliance and move everything out of Windows vCenter Server. The challenge is you lost data if you have integrated vCenter Server with other VMware products, or using DVS.

VMware released vCenter Server Migration Tool after VMworld 2016. It gave me confidence to give it a try. I assume vCenter Server is embedded SSO. I did the migration 2 or 3 times, following is summary of my experience. The migration tool only support migrate vCenter Server 5.5 windows edition to vCenter Server 6.0 U2.

Prerequisites

1. vCenter Server is more like core services today since lot of 3rd party software call vCenter API to interactive with VMs. You may have some products integrated with vCenter Server already. Please upgrade to vCenter 6 compatible version before migration.
2. I suggest create a local account on source vCenter Server if your server is domain member. You can login back source vCenter by local account in case migration failed.
3. vCenter Server Migration Tool applies temporary IP address on destination vCenter virtual appliance during migration. It’s used to communicate with source vCenter. Please register a temporary IP address for destination vCenter Server.
4. A helper VM is required to run migration image. Please make sure you have a free Windows VM be ready to mount migration image.
5. SQL database is exported to source vCenter Server if you want migrate performance and event data. So you need to make sure enough space on C: drive on source vCenter. The free space should be much bigger than vCenter database size.
6. Of course you need a vCenter Server 6 license key since old key doesn’t support the version.
7. Some cases show migration process stopped during export SQL database. That’s because memory of source vCenter is too small. Please make sure RAM of source vCenter should be equal or greater than destination vCenter Server.
8. The other tricky is database table. You may see migration processes is completed but destination vCenter Server doesn’t come up, and no data actually imported. That’s because ‘checksum‘ column existing in table [dbo].[VMO_ResourceElementContent] in vCenter DB. You can run following SQL query to remove it before migration.

   alter table dbo.VMO_ResourceElementContent drop column checksum;

Procedure

The items above can be done anytime before the migration window. Following steps should be token during migration.

1. You need to disable firewall and anti-virus software on old vCenter to avoid communication issue between Migration Assistant and new vCenter Server.
2. To avoid any unstable, resource contention, or potential network connectivity lost issue, I suggest temporarily disable DRS and HA on source and destination cluster if they are virtual machine.
3. Copy Migration Assistant from migration image to old vCenter.
4. Take snapshot on old vCenter and backup database of old vCenter.
5. Connect to console of source vCenter and run Migration Assistant.
6. Mount vCenter Server 6 U2m image on helper VM. Launch vCenter migration. The migration process is straightforward. I wouldn’t introduce more here.

After Migration

Basically you need to revert all the temporary changes made before. Such as delete snapshot and DB backup, enable DRS and HA, and disable vNIC on source vCenter Server to avoid any human error.