Convert a virtual disk from IDE to SCSI

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We recently deployed a new customer in our datacenter, who was migrating his servers from an on-premise Hyper-V cluster towards our VMware vCloud. Their sysadmins brought us their VM already converted in VMware format, so we started immediately to import them in our vSphere 5 clusters.

Sadly, VMs converted from Hyper-V have their boot disk in IDE mode instead of SCSI. This issue brings to low performances and other problems, such as the impossibility to use HotAdd mode in Veeam backups, or the ability to extend disk size.

Another reason for having IDE disk can be a conversion from a physical server having IDE disks itself. In all cases, it’s better to convert disks IDE disks to SCSI; let’s see how you can do it.

First of all, TAKE A BACKUP of the VM before doing anything!

Second, following VMware KB article 1016192 , shutdown the VM.

Via shell or ssh, go into the directory of the VM inside the datastore, and edit with VI the file .vmdk of the hard disk.

Look for the line:
ddb.adapterType = “ide”
and change it to:
ddb.adapterType = “lsilogic” (or another type like buslogic, based on which one is suggested for the guest OS)

Go to VM settings, and remove the hard disk and BE SURE to select “remove from virtual machine” and not “remove from virtual machine and delete files from disk”

Then add a new hard disk, choosing “Use an existing virtual disk” and selecting the previous hard disk. The SCSI ID should be SCSI 0:0

Last, check the IDE cd-rom and move it to a master position(0:0 or 1:0), since it can be on a slave and IDE bus does not accept a slave without a master (and that master probably was your disk you just converted to SCSI).

Now the VM can be booted, and it will have its disk connected to the SCSI controller. In a Windows OS, it will require another reboot to save the hardware change.

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