VMware
 

Knowledge Base

Search the Knowledge Base:
Products:
Search In:
 

Committing snapshots generates a content ID mismatch error

Symptoms

  • Performing a commit of a snapshot fails
  • The virtual machine shuts down abruptly during snapshot commit
  • Performing a snapshot commit generates the error:

    Content ID mismatch
     
  • Powering on the virtual machine generates the error:

    Content ID mismatch

  • The virtual machine log contains the following:

    Sep 11 03:01:45.328: vmx| DISKLIB-LINK : Attach: Content ID mismatch (d504c2f0 != 62e0e8bf).
    Sep 11 03:01:45.331: vmx| DISKLIB-CHAIN : "/vmfs/volumes/48a1b01c-67422c6d-f5aa-00188b50e0ff/test/w2k3-lsi-64.vmdk" : failed to open (The parent virtual disk has been modified since the child was created).
    Sep 11 03:01:45.336: vmx| DISKLIB-VMFS : "/vmfs/volumes/48a1b01c-67422c6d-f5aa-00188b50e0ff/186-testing/w2k3-lsi-64-000001-delta.vmdk" : closed.
    Sep 11 03:01:45.342: vmx| DISKLIB-VMFS : "/vmfs/volumes/48a1b01c-67422c6d-f5aa-00188b50e0ff/186-testing/w2k3-lsi-64-000013-delta.vmdk" : closed.
    Sep 11 03:01:45.348: vmx| DISKLIB-VMFS : "/vmfs/volumes/48a1b01c-67422c6d-f5aa-00188b50e0ff/test/w2k3-lsi-64-flat.vmdk" : closed.
    Sep 11 03:01:45.352: vmx| DISKLIB-LIB : Failed to open '/vmfs/volumes/48a1b01c-67422c6d-f5aa-00188b50e0ff/186-testing/w2k3-lsi-64-000001.vmdk' with flags 0xa (The parent virtual disk has been modified since the child was created).
    Sep 11 03:01:45.355: vmx| DISK: Cannot open disk "/vmfs/volumes/48a1b01c-67422c6d-f5aa-00188b50e0ff/186-testing/w2k3-lsi-64-000001.vmdk": The parent virtual disk has been modified since the child was created (18).

Resolution

 
When a snapshot delete is requested:
  1. The CID of the disk being combined into is updated
  2. The virtual disk is updated with changes.
  3. The CIDs of the children (that are not being removed) are updated.
If a failure occurs during the combine process (I/O errors or running out of disk space), the combine process aborts. The CIDs of the supporting children files never get updated, resulting in mismatch.
 
Warning: Do not perform a Go To and do not Revert to the parent snapshot.
 
You must correct the snapshot parent/child relationship.
 
To correct the parent/child relationship:
  1. Log in to the ESX Server console and verify the CID of all the virtual disks. The current snapshot disks are identified in the virtual machine configuration file (.vmx).
  2. Examine the virtual disk header files to verify the CID and ParentCID of each member to ensure that they match all the way up the tree.
  3. When the one that does not match is found, update the ParentCID of the child to match the CID of the file next up the chain.
Note: For more information related to performing these steps, see Consolidating Snapshots (1007849).
 
The virtual machine powers on normally at this point.
 
You can safely continue to use the snapshot or perform the commit operation again. VMware recommends to perform the commit operation so that all changes found in the delta are written down to the next level of snapshot or base disk (if there was only one level of snapshot).

Additional Information

 

Feedback

Rating: 1 - Lowest 2 3 4 5 - Highest (1 Ratings)   

Did this article help you?
This article resolved my issue.
This article did not resolve my issue.
This article helped but additional information was required to resolve my issue.
What can we do to improve this information? (2000 or fewer characters)
Submit
Rating: 1 - Lowest 2 3 4 5 - Highest (1 Ratings)   
Actions
  • KB Article: 1007969
  • Updated: Aug 14, 2009
  • Products:
    VMware ESX
  • Product Versions:
    VMware ESX 3.5.x