Hi,
Sorry, trying to understand your HA setup. Each Site? how many Sites (aka Clusters) do you have? Or is this One Site (1 Cluster) with 2 Nodes (aka two machines/servers).
If you have 1 Cluster 2 Nodes which share a SAN/NAS for config-store files then... you must have downtime. You cannot have one node on a 10.3 version and the other on a 10.2.2 sharing the config-store and expect stability.
Also Web Adaptors must be of same version as ArcGIS Server
Luckily, 10.2.2. to 10.3 is, for the most part, is a painless upgrade. Just run the 10.3 install... ArcGIS Server handles stopping all services, upgrading the software and restarting the site. Unlike 10.1 to 10.2.2 which left some 'residue' and buggy things happening. For Web adaptors, install is not an upgrade. You must uninstall the web adaptor and install the new version.
Hopefully you are running a true Acceptance / Production or have some sort of Pre-production environment to run through first...Also, Im a strong advocate of documentation.. so get your greenshot image capture tool ready!
Workflow idea:
Copy all shared content (SAN/NAS) used by ArcGIS Server (for backup)
Apply Maintenance page on IIS
Stop one Machine/server (aka Node) in the cluster. - Id stop this using Windows Services (not through ArcGIS Admin or manager).
Run the 10.3 install on the running arcgis server.. finish.
Confirm the 10.3 arcgis server is running
Rollback point. (at this point, can still use one node if need be)
Uninstall Both Web Adaptors
Run the 10.3 upgrade on the Node that is off... finish
Start the ArcGIS Server node that is off (using windows services)
Verify that both machines are running the cluster
Install the first web adaptor
Join to the ArcGIS Server Cluster
Install the second web adaptor
Join to the ArcGIS Server cluster.
Verify.
Rollback: VM snapshots options.
There are other options if you dont have an Acceptance/Production silo environment.
- remove one of the nodes from the cluster... change its Directories/Logs/Config-store directory to local.
You would have 2 web adaptors and 1 arcgis server still running.
Upgrade the node that is now 'standalone'.
Verify its operation.
If good. Then put site in maintenance and upgrade the still live 10.2 to 10.3, keeping the SAN/NAS structure.
Verify.
Join the standalone to the cluster...
It will then use the shared directories.. delete the local ones created.
Hope that helps.