Repairing your vmdk header files…

Increasing the size of a disk when a snapshot exists or deleting the wrong folder on your vmfs volume, it’s something that probably has happened to all of us.

This usually means that you will either need to edit the current vmdk header file or even recreate it. Although it’s not a difficult task it’s still error prone cause it’s a manual task, the procedure is outlined in this KB article for those interested.

Eric Forgette(NetApp), also known of mbralign and mbrscan, wrote a script that automates the recreation of a vmdk header file. The script also gives you the option to verify a header and if it’s corrupt fix it. Eric posted his script on the NetApp community forums and it can be found here.

I especially like the “fix” option of which the following is an example output:

[root@x3 root]# vmdkdtool /vmfs/volumes/test/testvm/fixed-template.vmdk

vmdkdtool version 1.0.090402.
Copyright (c) 2009 NetApp, Inc.
All rights reserved.

/vmfs/volumes/test/testvm/fixed-template-flat.vmdk is 12884902400 bytes (12.0000004768372 GB)

size = 25165825 (current 25125)
sectors = 63 (current value 21)
heads = 255 (current value 3)
cylinders = 1566 (current value 106)

NOTE: A backup of the file will be made if you choose yes.
Shall I fix the descriptor file? yes
Creating a backup of /vmfs/volumes/test/testvm/fixed-template.vmdk
Fixed.

Head over to the NetApp communities and pick it up, definitely a must have for your toolkit.