Read my other 2 post how to deploy and setup vROM

How to upgrade vCenter Operations Manager 5.8 to vRealize operations manager 6.2 part 1
How to upgrade vCenter Operations Manager 5.8 to vRealize operations manager 6.2 part 2

Now we can start the migration. On the First Page you can now select if it’s a new environment or a migration. The migration will be next to each other so the old and the new appliance will keep collecting data until you decide your migration is successful.  If not just start over. So Select Import Environment and click Next.

vROM - migrate - import

Accept the EULA and click Next.
vROM - migrate - accept EULA

Enter a product key and click Next.
vROM - migrate - lic key

Now you have to select you source server. This is the ip address of you UI VM not the analytics VM ip address. Click Add source.  You will get an info pop-up screen with the information it will take 5 min.
vROM - migrate - select source p1
vROM - migrate - select source p2

Accept the certificate and click OK.
vROM - migrate - select source p3

Once the Source is correctly added you will see a green check mark. Click Next.
vROM - migrate - select source p4

If you installed any solutions on the 5.8 appliance, for example Log insight or hyperic, you will need to update these first. If you don’t then no data will be migrated to the new appliance from these solutions. Download the missing solutions from https://solutionexchange.vmware.com/store and click add solution to update them.  When all solutions are green status then click next.
vROM - migrate - 6 select solution

And click Finish to complete the wizard.
vROM - migrate - finish

Depending on your environment this can take a long time. My case just 5 min because it’s a home lab. In your production it can take up hours
vROM - migrate - import data progress

Check if it’s successful in the status column.
vROM - migrate - import success