Sharing Virtual Disks Among VMs using VMware* ESX Server

By Shirley Chen (Intel) (3 posts) on March 27, 2009 at 3:40 pm

As I was playing around in the VMware* VI Client, I noticed that I could create a virtual drive that can be shared between my VMs on different systems. This comes in handy in saving some disk space. It’s also a nifty trick and an excuse to play with another feature. Since the backup files are read-only files, it’ll be perfect to create this type of virtual disk and have all my VMs access the same virtual disk simultaneously.

When you Edit Settings for a specific VM, you have the option to add virtual hardware. So press on the Add button and choose the Hard Disk option. Hit Next and choose Create a new virtual disk. On the next page, you can choose the size for your new virtual disk and store the image either where you stored the virtual machine virtual disk or another database on the system. Now here’s the key part to make your disk shareable. On this same page, make you have Support clustering features such as Fault Tolerance checked. On the next page, you’ll notice the different device nodes. Your virtual machine should be defaulted on SCSI (0:0). But your new shareable disk needs to be on a separate SCSI controller. Therefore choose SCSI (1:0). The 1 is important to make sure it’s on a different controller. Under the Mode section, check Independent and choose Persistent so your changes are written to the disk. Keep clicking Next until you finish. A new SCSI controller will be added in the virtual machine properties. Click on that and under the SCSI bus sharing, choose Virtual so your new disk can be shared among your VMs on that server. Click OK on the properties page and watch the magic begin. You new virtual disk will start formatting. Keep in mind that it will take much longer to format than the normal virtual disk.

After my new disk was created, I was able to start up my VM and format the disk like any other virtual disk I’ve created. I was able to create the backup of the database for TPoX on that virtual disk. For my other VMs to see the disk, I just added a new Hard Drive hardware on the properties page of the other VMs. However, instead of creating a new virtual disk, I just chose using an existing virtual disk and pointed to the disk file path of the virtual disk I just created.

I was able to start them up and mount the disk normally to my VMs after adding the virtual disk to all my VMs, I just need to be careful to just add and not format the disk accidentally. The only trick now is that I have to do an extra step if I ever want to add/delete material in that disk from one VM. I need to unmount and remount the disk in all my VMs. Or you can just reboot the machines to save you the trouble of typing in the commands.

It’s a cool thing :-)

Categories: Manageability & Security
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Comments (5)

June 9, 2009 11:42 AM PDT

Aamir Yunus (Intel)
Aamir Yunus (Intel)Total Points:
345
Green Belt
 Shirley,
I just used this. I needed to share webserver data among multiple VMs. :)

Aamir
October 21, 2009 2:28 PM PDT


Carson		 Good directions. I had to click the "Support clustering features such as Fault Tolerance" option under the Disk Provisioning option when Adding the shared Hard Disk. When I added the shared Hard Disk to another Virtual Machine, I had to configure the new SCSI Controller to also use the "Virtual" setting in SCSI Bus Sharing.
November 30, 2009 7:13 AM PST


phil mccance		 thanks for the diretions...i also had to delete all snapshots for that VM before i could set the controller as a 'virtual' under scsi bus sharing
November 30, 2009 8:22 AM PST


phil mccance		 also...i notice that the snapshot capability goes away, due to the shared scsi controller...from vmware web site:

http://kb.vmware.com/selfservice/microsites/search.do?langua.....Id=1013158

This configuration change fails because the virtual machine has an existing snapshot. You cannot snapshot a virtual machine with a shared SCSI controller. Similarly, you cannot share a virtual machine's SCSI controller when the virtual machine is running on snapshots.

You must consolidate all snapshots on the virtual machine.

To consolidate all snapshots on the virtual machine:
Right-click on the virtual machine.
Select Snapshot.
Click Snapshot Manager.
Click Delete All.
December 21, 2011 6:23 AM PST


ABoulton		 I know this is an old topic but I had a question, are you able to set up the Virtual shared storage as Active - Active ?

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