Increasing disk space in VMWare

The parent virtual disk has been modified since the child was created

I googled and found a lot of people had this problem, but the solutions weren't very easy to decipher. It seemed like most people were getting a fix by adjusting the disk geometry written in the vmdk file to pre-expansion mode, or adjusting the CID's of vmdk files to match the new values.

The root of the problem, by the way, is that I expanded the disk while I had a snapshot available.

I looked at CID's first, because that's the easy fix. Unfortunately, my CID's matched.

Next up was C/H/S disk geometry. My old nemesis. I did not have a backup available, and not only that, I never have found a way to come up with magic C/H/S numbers. I delved a little further into my own system. I found two entries in log files that looked promising.

Within my vmware.log file, I saw the following:

 vmx| DISKLIB-LINK  : Attach: the capacity of each link is different (52428800 != 20971520)

Within my session log, I found:

Using log file /tmp/vmware-root/vdiskmanager.log

  Grow: 100% done.

The old geometry C/H/S of the disk is: 16383/16/63

The new geometry C/H/S of the disk is: 16383/16/63

Oh joy, no change in the C/H/S.

So I went back and fgrep'ed for references to those two numbers - 52428800 and 20971520. I found reference in the snapshot file to my original disk size, but frankly I was a little wary of just making an edit in that file - it's binary and you never know how a change to a file like that will affect things.

Doing a little math - I realized that (52428800 / 2048)/1024 = 25 - the new size of my disk in GB. That really didn't get me anywhere, but it did put me on the right path. I took another look at my master vmdk file, and noticed the following:

RW 4193792 FLAT "Windows XP Professional-f001.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f002.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f003.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f004.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f005.vmdk" 0
RW 2560 FLAT "Windows XP Professional-f006.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f007.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f008.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f009.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f010.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f011.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f012.vmdk" 0
RW 4193792 FLAT "Windows XP Professional-f013.vmdk" 0
RW 2100736 FLAT "Windows XP Professional-f014.vmdk" 0

All those numbers add up to 52428800, and if I look at the numbers up to 2560, they add up to 20971520.

I made a quick edit, cut out the disks below 2560 and pasted them into a new file. Voila - I can go into "edit virtual machine settings" and see the original 10GB disk without any errors.

Now, rather than just boot up the machine and try cloning via vmware-converter, I decided to take it a step further. I used the GUI to remove the snapshot. This takes a while. Once the snapshot is removed, I copied the lines back into the vmdk file, then booted for the first time.

Worked like a charm. I can't believe nobody (at least that I could google) in 4 years figured that one out.

Quick review:

Don't expand a disk when there is a snapshot
If you have, like I did, using:

vmware-vdiskmanager -x 25GB ./something.vmdk

And you are running vmware server 1.x (ESX I know is different, 2.x, I have no idea)

1. Cut out the extra disks in your vmdk to a new file. (probably the ones after the first small #
2. Using the server console, remove the snapshot
3. Wait until that is done...
4. Copy back in the extra disks
5. boot

If you didn't understand all of this, don't try it.