6.5.1

This chapter includes the following topics:
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Planning Downtime for Virtual Machines
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Downtime for Upgrading Virtual Machines
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Upgrade the Compatibility for Virtual Machines
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Schedule a Compatibility Upgrade for Virtual Machines
Planning Downtime for Virtual Machines
Plan downtime for each virtual machine during the upgrade process. Typically, this downtime occurs
during the virtual machine upgrade and the VMware Tools upgrade. Depending on your upgrade plan,
some virtual machine downtime might be required during the ESX upgrade.
If an ESX/ESXi host is not managed by vCenter Server, you cannot use vMotion to move virtual
machines. The virtual machines must have some downtime when the ESX/ESXi host reboots after
upgrade.
You might not have to shut down more than a single virtual machine at any given time. You can stagger
virtual machine downtimes to accommodate a schedule convenient to you and your customers.
For example:
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If your virtual machine users are located in diverse time zones, you can prepare by migrating virtual
machines to specific hosts to serve a given time zone. This way you can arrange host upgrades so
that virtual machine downtime occurs transparently outside business hours for that time zone.
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If your virtual machine users operate around the clock, you can delay downtime for their virtual
machines to normally scheduled maintenance periods. You do not need to upgrade any stage within a
certain time period. You can take as long as needed at any stage.
Downtime for Upgrading Virtual Machines
When you upgrade virtual machines, the required downtime depends on the guest operating system and
the type of upgrade you are performing.
When you upgrade VMware Tools, expect the following downtime:
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No downtime is required for vCenter Server.
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No downtime is required for ESXi hosts.
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For Windows guest operating systems, you must restart the virtual machines at the end of the
upgrade procedure, or later, for the upgrade take effect. You must always restart the virtual machine
after you upgrade VMware Tools and after you upgrade the virtual machine compatibility.
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For Linux guest operating systems, you must restart the virtual machine to load the new versions of
the VMXNET, VMXNET3, and PVSCSI drivers. You can also manually reload the drivers. To verify
that the drivers are configured in the Linux kernel and that the virtual hardware is available, see
Knowledge Base article, http://kb.vmware.com/kb/2050364. Note that manual restart is not required
for the Linux guest operating system using kernel version 3.10.
vSphere Virtual Machine Administration
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