I was discussing something with one of my former colleagues a couple of days ago. He asked me what the impact was of running VMware View in an environment without HA. To be honest I am not a View SME, but I do know a thing or two about HA/vSphere in general. So the first thing that I mentioned was [...]

I guess there are a couple of keypoints I will need to stress for those creating designs: New HA maximums 32 host clusters 320 virtual machines per host 3,000 virtual machines per cluster In other words: you can have 10 hosts with 300 VMs each or 20 hosts with 150 VMs each or 32 with 93 VMs…. as long as you [...]

A couple of months ago I wrote this article about a future feature that would enable HA to recover from a Split Brain scenario. vSphere 4.0 Update 2 recently was released but the release notes or documentation did not mention this new feature. I had never noticed this until I was having a discussion around this feature with one of [...]

The amount of retries is configurable as of vCenter 2.5 U4 with the advanced option “das.maxvmrestartcount”. My colleague Hugo Strydom wrote about this a while ago and after a short discussion with one of our developers I realised Hugo’s article was not 100% correct. The default value is 5. Pre vCenter 2.5 U4 HA would keep retrying forever which could [...]

On the community forums a question was asked around Campus Clusters and pinning VMs to a specific set of hosts. In vSphere 4.0 that’s currently not possible unfortunately and it definitely is a feature that many customers would want to use. Banjot Chanana revealed during VMworld that it was an upcoming feature but did not go into much details. However [...]

A colleague had a question around the maximum amount of host failures HA could take. The availability guide states the following: The maximum Configured Failover Capacity that you can set is four. Each cluster has up to five primary hosts and if all fail simultaneously, failover of all hosts might not be successful. However, when you select the “Percentage” admission control [...]

Got asked the following question today and thought it was valuable for everyone to know the answer to this: How is a host selected for VM placement when HA restarts VMs from a failed host? It’s actually a really simple mechanism. HA keeps track of the unreserved capacity of each host of the cluster. When a fail-over needs to occur the hosts [...]