Appendix 2: Configuring Maintenance Mode And Vmotion With Vcenter; Prerequisites; Introduction; Concept Of Maintenance Mode - Dell PowerEdge UPS 500T User Manual

13. APPENDIX 2: CONFIGURING MAINTENANCE MODE AND VMOTION WITH VCENTER

13.1.

PREREQUISITES

All Virtual Machine images have to be installed and configured on a file server. (Please refer to
VMware user documentation listed in
13.2.

INTRODUCTION

The Dynamic Resource Scheduler (DRS) application from VMware is used to provide load balancing
within the IT network. In particular, DRS is used to ensure the right resource capacity is available for
the data center load. A second application called vMotion in conjunction with DRS will enact
movement of Virtual machines from physical server to physical server in order to provide the best
load balance.
The Distributed Power Manager application will help maximize data center electrical power efficiency
by checking DRS for physical server utilization then using vMotion, will move Virtual machines to
servers in order to fully unload servers than idle them or power them down for maximum power
savings.
Dell uses the same vMotion capability when a UPS is in a critical power situation to move virtual
machines off of a server that has a critical power situation. Dell Multi UPS Management Console will
now write alarms/alerts into vCenter, which, in turn, will trigger vMotion.
VMware uses the term 'setting a server into Maintenance mode' to trigger the vMotion. It is called
this because before performing maintenance on server, the data center manager needs to clear the
Virtual Machines from the server.
13.3.

CONCEPT OF MAINTENANCE MODE

Both standalone hosts, and hosts within a cluster, support the maintenance mode. Only ESX/ESXi
Server 3.0 and later supports maintenance mode for standalone hosts.
A host enters or leaves maintenance mode only as the result of a user request. If the host is in a
cluster when it enters maintenance mode, the user is given the option to evacuate powered off
virtual machines. If this option is selected, each powered off virtual machine is migrated to another
host, unless there is no compatible host available for the virtual machine in the cluster. While in
maintenance mode, the host does not allow deployment or 'power on' of a virtual machine. Virtual
machines that are running on a host entering maintenance mode need to be either migrated to
another host or shut down (either manually or automatically by DRS).
When no more running virtual machines are on the host, the host's icon changes to include 'under
maintenance' designation and the host's Summary panel indicates the new state. The default
Dell MUMC – User Guide
P 164000119 Rev 0.03
Dell Multi UPS Management Console
Appendix 4 VMware references)
USER GUIDE
Dell.com
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