The below may not be correct, depending on your upgrade scenario:
- Is it from 5.0.6.x to 5.0.6.x?
- Or from 5.0.6.x to 6.0.0.x or 6.1? -- If talking about 6.1 then see this IC article
In general: it is not yet possible to upgrade the servers in a cluster one-by-one. You will need to shut down all servers in the cluster and upgrade them all.
That said, I don't know what is your network topology... and an upgrade scenario can and will change depending on that.
It could be that you have 2 clusters of Worklight Servers, each with its own database, and a load balancer that redirects app requests:
[load balancer]
| |
| |
| |
[WL cluster] [WL cluster]
-s -s -s -s -s -s -s -s
| |
[DB] [DB]
In such a case you can:
- Direct all traffic to one cluster
- Take down the other cluster, upgrade all servers, restart
- Direct all traffic to the upgraded cluster
- Take down the unupgraded cluster, upgrade all servers, restart
- Direct again the traffic to both clusters