Moved VMDK to new server/Guest/VM and lost data
Article ID: 393914
Updated On:
Products
Issue/Introduction
When moving a VMDK from "GUEST/VM 1" to "GUEST/VM 2" , "GUEST/VM 2" no longer has the same data that "GUEST/VM 1" had when it was powered off. When "Guest/VM 2" is powered on we see a period of missing data such as "the last week of data" resulting in "Data Loss"
Environment
VMware ESXI (All Versions)
Cause
The VMDK was running on a snapshot prior to the move. When the VMDK was moved to "GUEST/VM 2" Only the Base disk for the VMDK was moved.
As "GUEST/VM 2" only had access to the base disk and not the snapshot chain any changes made to the VMDK when running the snapshot will be lost. As when you manually point a VM to the "base disk" and power it "on" the VMDK will be written to. This invalidates the snapshot chain and any data in that chain will be lost as the snapshot chain is no longer consistent, as the snapshot pointers are no longer valid.
Resolution
As the snapshot chain is no longer consistent due to the changes made, you will have to Restore the VMDK from backup if the data from the missing period is needed.
To prevent this from happening in the future. The VMDK should be consolidated and then verification should be made that it is no longer running on snapshots before the VMDK is moved to the new Guest/VM. You can clone the VMDK to the new location as well which will consolidate the snapshots and leave the original VMDK untouched.
Reference KB
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