Troubleshooting Snapshot failure with "A specified parameter was not correct" on replicated Persistent VDI VMs with persistent disks
Article ID: 422409
Updated On:
Products
Issue/Introduction
This article shares the steps to troubleshoot and investigate scenarios where snapshot attempts specifically fail on replicated VDI machines on DR site while their Production side VDI counterparts function normally . Below are some of the symptoms that might be encountered:
- When attempting to take a snapshot of a persistent VDI clone with disk mode Dependent at a DR site using any Replication solution, the task fails in vCenter with error:
"A specified parameter was not correct: spec.deviceChange.device An error occurred while taking a snapshot: One of the parameters supplied is invalid."
- Entries similar to the below may be observed in the
vmware.logof the impacted VDI machine:
/vmfs/volumes/<datastoreUUID>/<vm_folder>/vmware.log
vmx| DISKLIB-LIB_CREATE : Failed to create link: A digest operation has failed (##)
vmx| Er(##) vcpu-X - DISKLIB-LIB_CREATE : DiskLib_CreateChild: failed to create child disk: A digest operation has failed (##).
- Snapshot attempts continue to fail with below error, even after removing digest-related entries associated with the '
digest operation has failed' warning as per "Error: An error occurred while taking a snapshot: A digest operation has failed" when taking snapshot of VM :
An error occurred while taking a snapshot: Invalid change tracker error code
Resolution
Follow these steps to isolate if the corruption(As described in the KB above) is in the Master Image or the replication stream:
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Manually upload/export the Master Image to the DR site.
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Deploy a test VM from this image and attempt a manual snapshot.
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Result A: If the manual snapshot fails, the Master Image is corrupted and needs to be rebuilt with the assistance from VDI vendor if needed
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Result B: If the manual snapshot succeeds, the Master Image is healthy. The issue is likely introduced in the replication method and hence the replication vendor needs to be engaged.
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Workaround:
To bypass the errors, change the disk mode of the flagged drives to Independent-Persistent following the Change Disk Mode to Exclude Virtual Disks from Snapshots .This setting prevents those specific disks from being included in the snapshot, allowing the snapshot operation to succeed with the remaining disks.
Note: A snapshot can only be generated if at least one disk remains in Dependent mode. If the Virtual Machine (VM) has only a single disk, or if all available disks are set to Independent-Persistent, the snapshot operation will be disabled for that VM.
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