So if you’re like me, better safe than sorry… than you’ve probably set your ESX 3.5 U2 HA cluster to “shutdown VM” instead of “Power off VM” or “Leave VM powered on”. By now most of you probably already noticed that when an isolation occurs HA will allow the VM to shutdown clean within 5 minutes. When the 5 minutes [...]

I clearly don’t know much about Citrix version of HA, but I do know a thing or two about VMware’s version of HA. The following are outtakes of the article over at DABCC: VMware’s HA is heavily dependent on DNS or alternatively hosts entries being in place. The VMware implementation is based on the Legato Automated Availability Management (AAM), in [...]

I’ve seen a lot misinterpretations of the new advanced HA option “das.allowNetwork”. What is this option for and when should I use it or shouldn’t is the most asked question. So let’s start with a little history, back in the days “pre 3.5 U2″ one could configure a cluster on multiple IP subnets without facing any problems, but this could [...]

Seva, a VMware Technical Account Manager, put together a cool table with the implications of a VirtualCenter crash. This is a follow up to my blog about VirtualCenter getting more important by the minute. I think the most important thing to remember is that the VM’s keep running whatever happens to your VC Server and HA will still work if [...]

There seems to be a lot of fuss about HA not being reconfigured when Update 2 is installed. The error message that appears: “HA Agent on <hostname> in cluster <clustername> in <datacenter> has an error Incompatible HA Networks: Host has network(s) that don’t exist on cluster members: <ip address>: Cluster has network(s) missing on host: <ip address>: Consider using Advanced [...]

A while back I wrote down all the HA advanced options. With ESX 3.5 Update 2 VMware added a couple extra advanced options, this is the complete list: das.failuredetectiontime – Amount of milliseconds, timeout time for isolation response action(with a default of 15000 milliseconds). das.isolationaddress[x] – IP adres the ESX hosts uses for it’s heartbeat, where [x] = 1‐10. It [...]

I’ve been asking around why the default isolation response has been changed from “power off” to “leave powered on”. It seems that this is done because a lot of customers had VM’s being powered off unnecessary. This happened because the service console or physical switches weren’t setup redundant and thus caused HA to kick in. In other words, for those [...]