Thursday, September 23, 2010

VMware Virtual Infrastructure 3 (VI3) - Adding a Raw Device Mapping hard disk grayed out

We still have a client who are still on VI3 and I had a maintenance window today to reconfigure their virtualized SQL cluster and while executing my plan, I ran into an issue with mapping a newly provisioned LUN as an RDM. While this isn’t much of a difficult problem to solve, I’d like to blog it in case someone happens to Google this problem for a quick answer.

So here I am going through the regular tasks of attaching a new disk to an existing virtual machine.



…and I get to the screen with:

A virtual disk is composed of one or more files on the host file system. Together these files appear as a single hard disk to the guest operating system. Select the type of disk to use from the choices below.


Create a new virtual disk

Choose this option to create a new virtual disk.

Use an existing virtual disk

Choose this option to reuse a previously configured virtual disk.

Raw Device Mappings

Give your virtual machine direct access to the SAN. This option allows you to use existing SAN commands to manage the storage and continue to access it using a datastore.


The problem I had was that the option is grayed out. Fortunately, I sort of knew what might be the problem so I navigated to the Configuration tab, Storage Adapters and found that the newly provisioned LUN hasn’t shown up yet:


What I ended up doing was do a quick Rescan (top right hand corner in the screenshot above) of on the HBAs, got the LUN to show up and then went back to adding the disk. From there on, the option was available.

I hope this post will end up saving someone’s troubleshooting time.

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