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Maintenance Mode Improvements in vSphere 6.0 Update 2

vSphere 6.0 Update 2 has launched and with it comes a very simple change with the way that VMs and Templates are evacuated from hosts that enter Maintenance Mode. In all prior versions, when a host enters Maintenance Mode, DRS will evacuate the host by placing all the running VMs, powered off VMs, and the templates on other hosts within the cluster.  However, under certain conditions the order of operations produces very different results.  For math geeks, (4+2)2 ≠ 4+2×2. 

Starting with vSphere 6.0 Update 2, when a host enters Maintenance Mode the host will evacuate all the powered off VMs and templates first, and then proceed to vMotion all the powered on VMs.  This is probably not something that most will consider a big deal, but for some customers this small change will have a big impact.

Picture a situation where external services are provisioning VMs that use templates and those templates are stored on the host entering Maintenance Mode.  While entering Maintenance Mode no operations can be performed against the host, including clone operations.  In environments with dense consolidation ratios, the time it takes to evacuate the powered on VMs can be several minutes.  That’s several minutes before a powered off VM or template is moved to a host where it can be cloned.  If the provisioning engine were to attempt to clone from a template on a host entering Maintenance Mode, the clone operation would fail. This becomes particularly apparent in vCloud Director and vRealize Automation environments. Failure to provision new instances impacts the reliability of the service being provided.

Maintenance Mode Order

There have already been several improvements vSphere 6.0 in regard to reducing host evacuation times, especially for powered off VMs.  Now that they are done first, the opportunity for this type of error is reduced significantly, which results in a higher quality of service provided to your consumers.

This entry was posted in ESXi, vCenter Server, vCloud Director, vCloud Suite, vSphere and tagged , on by .

About Matthew Meyer

Matthew is a Senior Technical Marketing Architect working on Software-Defined Data Center technologies specializing in VMware vSphere cloud platform products and services. His previous experience includes working as an architect in VMware's Cloud Infrastructure & Management Professional Services Organization where he consulted on projects for VMware's fortune 100 clients. Matthew holds many industry certifications including VMware Certified Design Expert (VCDX#69). Twitter: @mattdmeyer

7 thoughts on “Maintenance Mode Improvements in vSphere 6.0 Update 2

  1. Pingback: VMware TAM Source 8.11 – VMware Updates and General News

    1. Matthew Meyer Post author

      If the powered off VM or template is left on a host that is in Maintenance Mode, you could not perform any operation against those VMs. This include cloning. If a 3rd party application were to call vCenter to initiate a clone, and the VM was on the host that is in maintenance mode, the attempt would fail.

  2. R V Raman

    I’m not sure whether is this the right forum where I should post this question?
    I’m totally an VMware Illiterate, however, my question is , can I update MS Windows Server patches or hotfix’s on the Guest OS while the ESX host is in maintenance mode? if so can you please help me with instructions or guides?

    1. Matthew Meyer Post author

      No running VMs can be on a host that is in Maintenance Mode. Maintenance Mode is intended where host-level changes are being performed without impact to the running VMs.


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