The vROps HA conundrum
Simon Eady
One of the great new features included in vROps is High Availability, however when you look a little closer at how it works careful thought needs to go into whether you want to use it or not.
I have had several discussions with my colleagues on the subject about whether you should or should not enable it in any given deployment of a vROps cluster.
So the following are my thoughts and bullet points for you to consider when faced with same dilemma.
By its very name, I assumed wrongly that it could be used as a way to tackle BC/DR concerns, it turns out the HA feature cannot span multiple logical datacenters - KB article - Forum discussion. I am hoping in future editions this gets resolved as it would be -very- handy.
So what other things do I need to take into account?
- The Master node behaves like an index for your cluster, lose it and lose your cluster, so HA can protect it although is no substitute for a proper backup solution. “.. Global xDB is used for data that cannot be sharded, it is solely located on the master node (and master replica if high availability is enabled)”
- HA takes several minutes to “kick in” so one could argue why not rely on vSphere HA (especially if your management cluster is tight on resources)
- HA would protect you against a LUN/Datastore failure assuming you had sensibly separated your nodes.
- HA adds an additional node so if you are tight on resources it might not be an option for you.
- Removal of data nodes (if you need to downsize your cluster) will result in data loss unless you have HA enabled.
The bullet points are by no means exhaustive but they are essential information while you muse your design choice for you next vROps cluster.
If you are looking for good reference material I can recommend the book Mastering vRealize Operations Manager by Scott Norris.