While browsing the VMTN community forums today, I noticed a very interesting post about mounting the CD-ROM device from within ESXi. The solution involved the use of vsish as the traditional mount utility did not function as expected in the Busybox Console of ESXi. I thought this was a very clever solution and might be worth sharing for those that may have similar needs.

Note: This trick looks like it only works with ESXi 4.1, as previous releases of ESXi may not include the iso9660 VMkernel module.

First you will need to load a VMkernel module: iso9660 which will allow you to mount and access the CD-ROM device.

You will need to run the following command:

vmkload_mod iso9660

You should see a successful message after the module has loaded:

Note: To see a list of VMkernel modules that can be loaded/unloaded, take a look at /usr/lib/vmware/vmkmod

Next you will need to identify the path to your CD-ROM device, you can do so by using the esxcfg-mpath utility.

You can run the following shorthand command to locate the path:

esxcfg-mpath -b | grep "CD-ROM"

You should see something in the form of mpx.*:

Now we will use vsish to perform the mount operation. Before we get started, if you did not perform the VMkernel module load of iso9660, you would not see the following path in /vmkModules/iso9660. Once the module has been loaded, you can perform a "ls" (listing) of the operations supported by this module which is mount and umount. You will need to run a "set" operation on the "mount" command and specify the device in which you would like to mount.

You will need to run the following command:

vsish -e set /vmkModules/iso9660/mount $(esxcfg-mpath -b | grep "CD-ROM" | awk '{print $1}')

If you do not see any messages after executing the command, it was successful, else you may see an error/warning for incorrect syntax.

The CD-ROM device will automatically be mounted under /vmfs/volumes/mpx.* and there will also be a symlink with the CD-ROM label. In this example, I mounted an ESXi 4.1 Update 1 ISO file.

We can change into the directory to confirm we actually have the CD-ROM device mounted and list the contents.

Once you are done with your task, to umount is the same syntax except you will be using the "umount" operation. You can unmount by using the following command:

vsish -e set /vmkModules/iso9660/umount $(esxcfg-mpath -b | grep "CD-ROM" | awk '{print $1}')

Another alternative is to mount the image on another system and copy the contents to your ESXi host, but if you only had your ESXi host and needed to pull something from a CD-ROM, this is how you would do it.

Thanks again to agodwin for sharing this tidbit.