Just as a conventional CPU has specific files that keep the machine running properly, there are files and collections of files on a virtual machine that do the same.

The VMDK flat files store the content that is on the hard disk drives of a virtual machine. VMDK files (without the word “flat” preceding dot-vmdk) are the disk descriptor files, which contain all information regarding its associated flat file. 

Meanwhile, VMDK Delta files, created during backups when a snapshot of a virtual machine hard drive is taken, store content from the time the snapshot was created until the time the snapshot is complete and operations return to normal. These files are then reconciled for an up-to-date snapshot, with all recent file changes reflected. These files also have corresponding disk descriptor files.

Signs of VMDK File Corruption

If any of these files on your virtual server or servers become corrupt, the machine may fail to power on. This may occur if:

– a descriptor file is missing

– the description section of the VMDK flat file is missing or incorrect

– a VMDK or VMDK flat file is corrupt

If a VMDK file is missing or corrupt, you may see one of the following errors when you power on your virtual machine or in the log files: 

“Failed to power on. A file was not found.”

“Unable to find file”

“The system cannot find the file specified.”

If you receive one of these error messages, you may be able to re-create the missing VMDK file or re-name it properly. The steps to do this will vary depending on what platform your virtual server is running on, whether it’s Windows, Unix, Linux, or Mac OS X.

If something goes wrong and you can’t get your virtual server to boot, and you keep receiving “File not found” errors, it may be time for emergency data recovery services.

24 Hour Data’s VMware recovery experts stay up-to-date on the latest virtualization techniques and data recovery for every virtualization platform. Before you attempt do-it-yourself data recovery techniques that may be unfamiliar to you, give us a call for an honest price quote — the cost may be less than you expect, and we’ll have your lost data back to you within about 48 hours or less.

Source: http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd…