Thursday, February 6, 2020

Migrate vRealize Orchestrator 7.3 Cluster with External Database to 7.6

In every environment's life comes a time when you need to upgrade. So it did happen for our vRO setup. The source environment is running vRO 7.3.1 in a 2-node cluster and with and external MSSQL database. The target environment is a 2-node cluster running vRO 7.6 and internal PostgreSQL (since no external is supported).

Because source vRO is connected to external MSSQL server, in place upgrade is out of the question. So a migration is actually the only way to do it. A constraint for the migration is not to change hostnames or IP addresses. Well, the requirement is actually to get everything back to 7.6 with a minimum of reconfiguration and here we talk about plugins, workflows, actions, configuration elements, certificates and all that jazz.

Having laid down the task ahead we started working on the plan. And what we came up with was pretty interesting. 

vRO 7.6 appliance offers a migration tool that is accessible through VAMI. The tool needs access to source vRO and database. Since we have a 2-node cluster, we'll take advantage of that and do a rolling migration. Source vRO 7.3 cluster is made of nodes: node1 and node2. Target vRO 7.6 cluster will be running the same vRO nodes.

So how does this rolling migration look like:

In initial state there is a vRO 7.3.1 cluster with external MSSQL database. We start by redirecting traffic in load balancer to node1 and disabling monitoring on the pool. Then we break the cluster by removing node2 and powering it off. Next we deploy a new node2 running 7.6 and using the same hostname and IP address. If you want to reuse the same VM name, you just need to rename the old node in vCenter Server.

This takes us to intermediary state where we have one node1 in 7.3.1 and node2 in 7.6 with and embedded PostgreSQL DB. Once node2 in 7.6 is up an running, we connect to VAMI and fire up the migration tool. Migration tool will transfer all data from node1 and the external DB to node2. After vRO is migrated to 7.6, we proceed to power off node1 running 7.3.1 and deploy node1 in 7.6. Don't forget to switch over traffic to node2 in load balancer.

Now we are in final state where both nodes are running 7.6. Once node1 is up, we add it to the cluster that node2 is already member. The cluster is back and this time running vRO 7.6 with embedded PostgreSQL database. Simple, right?

Well, there are a few of gothcas:
- when running the migration tool, a pre-check is run that can fail if the vRO DB contains duplicates; it can be fixed by either removing duplicates from DB or connecting with vRO client to source vRO and renaming them
- SSL certificates are not migrated - you need to connect to source vRO keystore and export the certificates, then re-add them in control center
- there is a cumulative update that needs to be applied to the freshly deployed vRO 7.6
- dynamic types plugin configuration is not migrated - there is an updated plugin that needs to be installed
- in some cases you may need to update the appliance hardware including file system

Lastly enable traffic in load balancers to both nodes and re-enable health monitors. Do that after importing SSL certificate.

Happy migrations!

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