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After cold migration on ESX Server, virtual disk with snapshot has the wrong CID
Details
If a virtual machine has a snapshot, cold migrating it with VirtualCenter from one ESX Server host to another changes the context ID (CID) of the parent virtual disk. The change causes a boot failure, with the error message A general system error occurred: Internal error. The vmware.log file contains the message The parent virtual disk has been modified since the child was created. (The parent is the virtual disk before snapshot, while the child disk is the snapshot.)
The cause is that although the CID and parent CID of the child disk (the snapshot) are migrated correctly, the CID of the parent disk is not, so the migrated snapshot cannot locate its parent VMDK.
Solution
You can manually correct the parent CID by modifying its VMDK file with a text editor.
The child snapshots have sequence numbers. Verify that each child refers correctly to the previously numbered snapshot. The first snapshot, WinXP-0001.vmdk for example, contains a line such as parentCID=c9753ea9. Note this number. With the migrated virtual machine powered down, edit the parent disk, WinXP.vmdk in this example. Change its CID= line to match the number you noted above. The parent VMDK always displays parentCID=ffffffff to indicate it is the base disk. Do not change that line.
If the virtual machine has multiple snapshot disks, check and correct the CID of all parent disks.
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- KB Article: 1005228
- Updated: Aug 14, 2009
- Products:
VMware ESX
VMware VirtualCenter - Product Versions:
VMware ESX 3.5.x
VMware VirtualCenter 2.5.x