VMware 4.0: maintenance mode vs shutdown, which in which situations?

I have to move a SAN to a different UPS temporarily.  I saw that sometimes people use maintenance mode and other times they simply shut everything down and power off.  Can someone explain maintenance mode and why I'd want to use it vs. just shutting down?  Thanks.
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LB1234Asked:
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Maintenance Mode when enabled on a Host ESX or ESXi server prevents a VM being powered ON that host.

It also removes it from being used in the cluster .

If we are performing SAN work we like to

1. Put Host in Maintenance Mode
2. Shutdown Host
3. Shutdown SAN.

Power up is reverse and End with Exit Maintenance Mode
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LB1234Author Commented:
Thanks for the insight.  Does putting the host into maintenance mode initiate VMotioning the resident VM's to another host?    I'm assuming I shut off the VM's before entering maint. mode.
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
If you have a Cluster with HA Enabled and DRS set to Automatic....

Entering Maintenance will evacuate the host!

After All VMs are moved OFF via vMotion the Host then enters Maintenance Mode...

Another good reason to put in Maintenance Mode otherwise you would have to manually Migrate vMotion each VM.
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