Bug in Cluster mem.usage.average Statistic in vSphere 4.0 U1 @ Jonathan Medd's Blog

Bug in Cluster mem.usage.average Statistic in vSphere 4.0 U1

Posted on February 23rd, 2010 Jonathan Medd 5 comments

A while back I posted a script on a basic capacity report I run each month to get an overview of CPU and Memory usage in our various clusters. Since upgrading to vSphere 4.0 U1 I noticed some strange behavior in the results for memory, i.e. they came back at pretty close to 0% (typically between 0.05 and 0.06%) for the average memory usage in a cluster which typically were quite heavily used. On investigating further this also appeared the same in the GUI.

Using Get-Stat, mem.usage.average comes back at 0% where it should be a significant value:

The same in the GUI, the other cluster memory stats have significant values, but Memory Usage Average flatlines along the bottom of the graph:

This stat shows normal behaviour against host machines. I reported it to VMware who confirmed it to be a bug in 4.0 U1.

Thought I would share in case anyone else spends some time scratching their head and checking maths in scripts like I did. I’ll post back when there is a fix.

Update 19/05/2010:

Just got a follow up email from VMware Support that this bug will be fixed in VC 4.0 U3 – no release date for that yet.

Update 01/06/2011:

Thanks to Michael for pointing out in the comments that this is confirmed fixed in VC 4.0 U3. I make that 1 year + 1 month from the time of reporting the issue to it being resolved in an available fix

http://www.vmware.com/support/vsphere4/doc/vsp_vc40_u3_rel_notes.html#resolvedissues

powercli, vmware powercli, vmware
5 responses to “Bug in Cluster mem.usage.average Statistic in vSphere 4.0 U1”
- NiTRo February 24th, 2010 at 19:33
  
  I got 0,02% in my VC
  Sounds we need to use consumed/total metric
- Jonathan Medd February 24th, 2010 at 20:48
  
  Thanks for the comment. VMware says the figure may just be out by a factor of 100 so not too difficult to temporarily fix in my script.
  
  Sent them some more screenshots today so hopefully it will get fixed soon.
- NiTRo February 28th, 2010 at 13:57
  
  Your post give me a great idea : a capacity planner script in powershell
  http://www.hypervisor.fr/?p=1890
- Michael May 29th, 2011 at 18:21
  
  Solved in Update 3:
  vSphere Client displays incorrect values for the percentage of memory usage of cluster entities.
  On the Performance tab of vSphere Client, a graph displays memory usage counters (for example, Average, Minimum, and Maximum). For cluster entities, the percentage values displayed for these memory usage counters are incorrect.
  
  Translation logic is missing for converting the metric value from kilobytes (KB) to bytes (B). The result is that the same metric unit is not used for the numerator and denominator when calculating the memory usage counters in percentage units at the cluster-entity level.
  
  This issue is resolved in this release.
  
  http://www.vmware.com/support/vsphere4/doc/vsp_vc40_u3_rel_notes.html#resolvedissues
- Jonathan Medd June 1st, 2011 at 14:16
  
  Thanks for pointing it out, it was so long ago that I forgot to check when U3 was released. Had long since moved to 4.1 where the issue does not exist.
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