We had a discussion internally around memory limits and what the use case would be for using them. I got some great feedback on my reply and comments so I decided to turn the whole thing into a blog article. A comment made by one of our developers, which I highly respect, is what triggered my reply. Please note that [...]

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 [...]

Not sure why hardly anyone picked up on this cool youtube movie about Storage IO Control(SIOC), but I figured it was worth posting. SIOC is probably one of the coolest version coming to a vSphere version in the near future. Scott Drummonds wrote a cool article about it which shows the strength of SIOC when it comes to fairness. One [...]

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 [...]

By now the whole world has probably read that vSphere 4 Update 2 has been released. (release notes vCenter, release notes ESX, release notes ESXi ) Some of you might have even started slowly upgrading their test systems. (Like I am doing at the moment…) I will not copy the full release notes but I do want to point out a [...]