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I'm labbing-up VMware's DPM (Dynamic Power Management) technology this week.  This is a self-funded home lab, and I'm too cheap to use enterprise-grade hardware.  That means technologies like IPMI/iLO are out of the question.  The good news is that both of my lab hosts support Wake-on-LAN (WOL). 

I went into the BIOS of each of the ESXi hosts and enabled Wake-On-LAN.  I placed both of them into a cluster and enabled DPM.  I then attempted to place one of the hosts into standby mode.  The vCenter client complained with the following message:

vCenter has determined that it cannot resume host lab1.example.com from standby; therefore, the enter standby task was stopped.  Confirm that IPMI/iLO is correctly configured for host lab1.example.com.  Or, configure vCenter to use Wake-On-LAN, ensuring there are at least two or more hosts in the cluster, and try the task again. 

That last line really bugs me because there is no WOL-specific configuration options in vCenter.  After a little digging around (RTFM) I read that vCenter must be able to send the WOL "magic packet" to a physical NIC where vMotion is enabled.  I had not yet enabled vMotion on these two lab hosts!


After enabling vMotion on my hosts, I was able to successfully place them into standby mode.  Even more importantly was the fact that vCenter could wake them back up again. 


I observed one other quirky behavior with DPM.  When attempting to manually power-on the sleeping host, vCenter's "please wait" message reads:

 Waiting for host to power off before trying to power it on

This comes AFTER I get confirmation that the "Host is in Standby Mode".  It could be that vCenter still isn't sure if the machine is fully powered-off just yet, so it's waiting an arbitrary amount of time before sending the WOL packets to my host.  I'll have to play with it a little more and see if vCenter gives the same misleading "please wait" message when powering-on a host that has been sleeping for a while.