SSH access to your ESX host
Equal or more amount of space on your LUN to the size of your vmdk file
In order to convert your vmdk file you will need to SSH to your ESX host and cd to appropriate LUN with affected vmdk file. Check content of folder by issue ll command.
In this scenario we will be working with VM1_ide.vmdk file. Take a note of the size of the flat vmdk file.
Now we need to create SCSI vmdk file with same size. Issue the following command:
[root@esx04 VM1]# vmkfstools -a lsilogic -c 10737418240 VM1_scsi.vmdk
New file name will be VM1_scsi.vmdk
do ll once more to see what happened
We can delete VM1_scsi-flat.vmdk file, as we not going to use it.
Now open VM1_scsi.vmdk in editor
[root@esx04 VM1]# nano VM1_scsi.vmdk
Here we need to replace VM1_scsi-flat.vmdk with VM1_ide-flat.vmdk. Actualy point to ide flat disk. Save after edit.
Now edit your .vmx file and replace VM1_ide.vmdk with VM1_scsi.vmdk
Re-register your VM with Virtual Centre and start VM.
For safety precautions I've put this disk and others into Nonpersistent mode for first test start, so in the event of OS (mostly MS windows) failed to recognize drive, changes will be discarded as soon as I shutdown VM.
This scenario works for me for 3x 200gb disks.
Any comments more than welcome.