VMDK Flat File is 0 bytes - can I recover the data

[boardy89]

I recently tried to upgrade Vmware ESXI 6.0 to 6.6 which I am now rather regretting. I backed up all the VM from the server before completing the upgrade and unfortunately all the VMs that I wouldn't be too bothered if they broke are working fine, however, the 1 server that I really didn't want to break has.

The server was setup as NAS with 2 disks, one containing the OS and the other containing data for the NAS, such as network shares etc.

Disk 1 appears to be fine, it can boot up the OS, although I think the OS install is a little corrupt but it at least tries, but only if the second disk is not included. If the second disk is in the virtual machine config the VM fails to boot.

In the log file I have:

2017-05-05T20:09:28.440Z| Worker#1| I120: UTIL: Change file descriptor limit from soft 4096,hard 4096 to soft 4211,hard 4211.

2017-05-05T20:09:28.446Z| vmx| I120: DISKLIB-VMFS  : VmfsExtentCommonOpen: possible extent truncation (?) realSize is 0, size in descriptor 2684354560.

2017-05-05T20:09:28.446Z| vmx| I120: DISKLIB-VMFS  : "/vmfs/volumes/590b9a4f-ab837c7e-4af0-941882371170/NAS/NAS_1-flat.vmdk" : failed to open (The file specified is not a virtual disk): Size of extent in descriptor file larger than real size. Type 3

2017-05-05T20:09:28.446Z| vmx| I120: DISKLIB-LINK  : "/vmfs/volumes/590b9a4f-ab837c7e-4af0-941882371170/NAS/NAS_1.vmdk" : failed to open (The file specified is not a virtual disk). 

2017-05-05T20:09:28.446Z| vmx| I120: DISKLIB-CHAIN : "/vmfs/volumes/590b9a4f-ab837c7e-4af0-941882371170/NAS/NAS_1.vmdk" : failed to open (The file specified is not a virtual disk).

2017-05-05T20:09:28.446Z| vmx| I120: DISKLIB-LIB   : Failed to open '/vmfs/volumes/590b9a4f-ab837c7e-4af0-941882371170/NAS/NAS_1.vmdk' with flags 0xa The file specified is not a virtual disk (15).

2017-05-05T20:09:28.446Z| vmx| I120: DISK: Cannot open disk "/vmfs/volumes/590b9a4f-ab837c7e-4af0-941882371170/NAS/NAS_1.vmdk": The file specified is not a virtual disk (15).

2017-05-05T20:09:28.456Z| vmx| I120: DISK: Opening disks took 48 ms.

2017-05-05T20:09:28.456Z| vmx| I120: Module Disk power on failed.

I've looked at some community pages about re-creating the description file but I don't think this is going to work unless I am missing something as it looks like the flat file, in this case NAS_1-flat.vmdk should be a large file as it contains that actual disk contents, however, for me its for some reason 0 bytes - I unfortunately didn't notice this.

I have the following vmdk files for NAS_1 disk

• NAS_1.vmdk
• NAS_1-000001.vmdk
• NAS_1-000001-delta.vmdk

I also have 2 snapshot files as well if that helps.

I have a copy of VMWare ESXI and VMWare Workstation so I tried loading the VM into that, as thought as its the paid version may offer some repair functionality but alas no. I've also tried giving the VM the delta disk instead of the flat file but it states disk needs repair but doesn't give me any options or instructions on how to do this.

So, can I recover the disk from what I have, or as I expect will be the answer, am I screwed .

Thanks for any help or suggestions you might have.

[a_p_]

Welcome to the Community,

if the flat file is gone, there's unfortunately not much you can do other than resorting data from backup, or trying to recover the file on the datastore (if you want to try this, I'd suggest you contact community member continuum​).

Anyway, if you don't have a backup, it might be possible to recover at least some data from the snapshot(s). The larger the snapshot, the better are chances to recover some data.

To find out what may be possible, please post a complete list of files in the VM's folder on the datastore, i.e. the output of ls -lisa from the command line. In addition to this, compress/zip the VM's .vmx, .vmsd, .vmdk (only the small descriptor files, not the flat/delta files) as well as the vmware*.log files, and attach the archive to a reply post.

André

[Sreejesh_D]

it may be due to broken snapshot chain. I would recommend to open a ticket with VMware support. They will help you to fix it.

[boardy89]

Thanks for the reply, I thought that was likely going to be the case. Unfortunately the backups I have aren't the most recent (that will teach me) the latest backup is the backup I have of the VM itself which for some reason didn't work properly.

I'm guessing I won't be able to recover much from the snapshot, I think from memory there should be around 1TB of data, however, the snapshot is only 125GB.

The files I have in the vm are as follows:

• NAS.nvram
• NAS.vmdk
• NAS.vmsd
• NAS.vmx
• NAS.vmf
• NAS_1.vmdk
• NAS_1-000001.vmdk
• NAS_1-000001-delta.vmdk
• NAS_1-flat.vmdk
• NAS-000001.vmdk
• NAS-000001-delta.vmdk
• NAS-flat.vmdk
• NAS-Snapshot2.vmem
• NAS-Snapshit2.vmsn
• Then there's log files vmare.log, vmware-3.log through to 10.

Thanks

[TheBobkin]

Hello Boardy,

Where are you seeing the -flat as being 0KB size - From the vSphere Client/Datastore Browser?

If so, then consider ignoring this for a moment and go to the source:

- SSH to any host that has this datastore accessible

# cd /vmfs/volumes/DatastoreName/VM_Name

# ls -lah

What size does this show? (attach screenshot or copy+paste if you can).

I ask this as from the logs I don't see it bombing-out when it tries to open or close the disks,  which it would likely do if they were indeed 0KB.

Bob

-o- If you found this comment useful please click the 'Helpful' button and/or select as 'Answer' if you consider it so, please ask follow-up questions if you have any -o-

[boardy89]

Hi Bob,

I'm seeing the 0 bytes from SSH into ESX host and ls -l into the directory as you suggested, not from the datastore.

Thanks

Chris

[continuum]

>VmfsExtentCommonOpen: possible extent truncation (?) realSize is 0, size in descriptor 2684354560.
Not good !
Anyway - if you provide a VMFS-header-dump - see Collecting and applying raw metadata dumps on VMFS volumes using DD (Data Description) (1020645) | V...
I may be able to help.
Call me via skype
Ulli