PowerPath on Virtual Machine

Thanx for your confirmation dynamox!!

nope ..don't need it for virtual machines.

I wonder in what case you would need virtual HBAs with virtual luns. What is the point of that? Can someone think of an example on when we would need it?

Dynamox is right... as long as you are only planning on assigning LUNs to the ESX server itself, then carving it up to share with the virtual servers.

I believe (from talking to my server guys) that ESX 3 also offers the ability to assign virtual HBAs to virtual hosts and give LUNs directly to the virtual machines. If you do this, you would need PowerPath (or some method of managing multiple paths) on the virtual machine.

If you need to use Solutions Enabler / SYMCLI to query/manage a Symmetrix from within a virtual machine, you would need to present that VM with a so called "gatekeeper" device (LUN).

This gatekeeper would have to be presented via a virtual HBA to allow the required low level SCSI commands to reach the array.

An example might be a backup script which controls TimeFinder or SRDF copies of the data via SYMCLI. Another would be the requirement to use symconfigure from within a VM.

BTW - I'm fairly sure that you can create virtual SCSI HBAs for this in ESX v2.x

Best Regards,
Marc

There are times that you may want to better control the performance characteristics of the disk available to a virtual server. The only way to do this completely is to assign LUNs directly to the virtual host, and bypass the ESX level entirely. As far as the host and array are concerned they are directly attached (through a SAN) instead of having the virtualization layer in between.

Remember, virtualization isn't ALWAYS better.