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Uptime lost during VMotion

by Roger Lund

Jason Boche, has a interesting post titled Uptime lost during VMotion


Jason walks us through this , http://www.boche.net/blog/index.php/2009/01/11/uptime-lost-during-vmotion/

Please check it out, below are a few blips from the post.


That’s right.  We lose uptime during every VMotion.  Relax just a bit – I’m not talking about actual uptime/downtime availability of the guest VM in the datacenter.  I’m speaking to the uptime performance metric tracked in the VirtualCenter database.  It’s a bug that was introduced in VirtualCenter 2.0 and has remained in the code to this day in VirtualCenter 2.5.0 Update 3.

My personal opinion is that the intended use of the Virtual Infrastructure Client is for the VMware administrator and thus should reflect virtual infrastructure information.  My preference is that the uptime statistic in VirtualCenter tracks power operations of the VM irregardless of any reboot sequences of the OS inside the VM.  In other words, uptime is not impacted by VMware Tools heartbeats or reboots inside the guest VM.  The uptime statistic should only be reset when the VM is powered off or power reset (including instances where HA has recovered a VM).

At any rate, due to the bug that uptime has in VirtualCenter 2.0 and above, it’s a fairly unreliable performance metric for any virtual infrastructure using VMotion and DRS.  Furthermore, the term itself can be misleading depending on the administrators interpretation of uptime versus what’s written in the VirtualCenter code.

I submitted a post in VMware’s Product and Feature Suggestions forum in January of 2007 recording the uptime reset on VMotion issue.  As this problem periodically bugs me, I followed up a few times.  Once in a follow up post in the thread above, and at least one time externally requesting someone from VMware take a look at it.  Admittedly I do not have an SR open.

VMware, can we get this bug fixed?  After all, if the hypervisor has become an every day commodity item leaving the management tools as the real meat and potatoes, you should make sure our management tools work properly.


Thanks Jason for bringing this up.

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