How to backup VM with two delta file through VDDK

dbackup — Fri, 19 Nov 2021 08:40:02 GMT

Hello, I have a Virtual Machine on ESXi 7.0:

Guest OS: Microsoft Windows Server 2016 (64-bit)
Compatibility: VmHardware.HWVersion.long.vmx-19
VMware Tools: Running, version:11333 (Current)

It has only one disk on SCSI controller 0:

Type: Thick Provision Lazy Zeroed
Disk File: [d2] 2016/2016.vmdk
Disk Mode: Dependent

quiesced snapshot part

After creating a quiesced snapshot, I found that it had two delta files(aka child disks) which is strange because only one delta file should be generated:

vCenter shows that the virtual machine is now using [d2] 2016/2016-000001.vmdk:

And Managed Object Browser shows that the disk recorded in the snapshot is [d2] 2016/2016-000002.vmdk

Obviously I can't open them READ ONLY through VDDK 7.0.3, NBD transport mode:

KLog: NBD_ClientOpen: attempting to create connection to vpxa-nfc://[d2] 2016/2016-000001.vmdk@192.168.88.230:902
KLog: Setting NFC log level to 1
KLog: Setting NFC log level to 1
KLog: NFC Async IO session is established for '[d2] 2016/2016-000001.vmdk' with log level 1.
KLog: Opening file [d2] 2016/2016-000001.vmdk (vpxa-nfc://[d2] 2016/2016-000001.vmdk@192.168.88.230:902)
KWarning: [NFC ERROR]NfcAioRcvErrorMsg: Error from server: NfcAioProcessOpenFileMsg: Failed to open '[d2] 2016/2016-000001.vmdk': DiskLib error 49: Thin/TBZ/Sparse disks cannot be opened in multiwriter mode
KLog: Fail to open file [d2] 2016/2016-000001.vmdk
KLog: DISKLIB-DSCPTR: : "vpxa-nfc://[d2] 2016/2016-000001.vmdk@192.168.88.230:902" : Failed to open NBD extent.
KLog: DISKLIB-LINK : "vpxa-nfc://[d2] 2016/2016-000001.vmdk@192.168.88.230:902" : failed to open (Thin/TBZ/Sparse disks cannot be opened in multiwriter mode).
KLog: DISKLIB-CHAIN : "vpxa-nfc://[d2] 2016/2016-000001.vmdk@192.168.88.230:902" : failed to open (Thin/TBZ/Sparse disks cannot be opened in multiwriter mode).
KLog: DISKLIB-LIB : Failed to open 'vpxa-nfc://[d2] 2016/2016-000001.vmdk@192.168.88.230:902' with flags 0xe Thin/TBZ/Sparse disks cannot be opened in multiwriter mode (49).
KLog: VixDiskLib: Detected DiskLib error 49 (Thin/TBZ/Sparse disks cannot be opened in multiwriter mode).
KLog: VixDiskLib: Failed to open disk vpxa-nfc://[d2] 2016/2016-000001.vmdk@192.168.88.230:902!52 26 a2 59 d8 1d 32 3e-af 4e c9 d9 18 f1 5e b5. Error 1 (Unknown error) (DiskLib error 49: Thin/TBZ/Sparse disks cannot be opened in multiwriter mode) at 6469.
KLog: VixDiskLib: VixDiskLib_OpenEx: Cannot open disk [d2] 2016/2016-000001.vmdk. Error 1 (Unknown error) (DiskLib error 49: Thin/TBZ/Sparse disks cannot be opened in multiwriter mode) at 7133.
KLog: VixDiskLib: VixDiskLib_Open: Cannot open disk [d2] 2016/2016-000001.vmdk. Error 1 (Unknown error) at 7211.
Failed to open

KLog: VixDiskLib: VixDiskLib_OpenEx: Open a disk.
KLog: 2021-11-19T16:19:01.733+08:00 error -[05958] [Originator@6876 sub=vimaccess] GetFileName: Cannot create disk spec for disk [d2] 2016/2016-000002.vmdk.
KLog: -->
KLog: VixDiskLib: Error occurred when obtaining the file name for [d2] 2016/2016-000002.vmdk. Error 1 (Unknown error) (Cannot create disk spec for disk.) at 3344.
KLog: VixDiskLib: VixDiskLib_OpenEx: Cannot open disk [d2] 2016/2016-000002.vmdk. Error 1 (Unknown error) at 7133.
KLog: VixDiskLib: VixDiskLib_Open: Cannot open disk [d2] 2016/2016-000002.vmdk. Error 1 (Unknown error) at 7211.
Failed to open

But I CAN open [d2] 2016/2016.vmdk to read, so I backup the whole [d2] 2016/2016.vmdk disk(not just allocated blocks) through VDDK.

Finally, I restored the disk to the virtual machine. And try to use it to start the virtual machine, but the blue screen is directly displayed when starting:

none quiesced snapshot part

So I created a none quiesced snapshot instead. And it has only ONE delta file as expected.

I backup [d2] 2016/2016.vmdk through VDDK 7.0.3 and restore to the virtual machine again. And the operating system can be turned on normally this time.

question

How do I back up this virtual machine with a quiesced snapshot?

Re: How to backup VM with two delta file through VDDK

dbackup — Mon, 22 Nov 2021 07:10:13 GMT

It turns out that i forgot to set up snapshotRef in VixDiskLib_ConnectEx, problem solved.

Re: How to backup VM with two delta file through VDDK

ocdata — Mon, 22 Nov 2021 22:35:24 GMT

Did you just have to pass in the snapshot ref name, like "snapshot-1234" into connectEX? I seem to be getting the same errors trying to open snapshot files from quiesced snapshots even when I supply the snapshot ref.

Re: How to backup VM with two delta file through VDDK

dbackup — Tue, 23 Nov 2021 08:04:37 GMT

Yes, snapshot MoRef is needed to open quiesced snapshot file in some circumstances, like double snapshot files.

Re: How to backup VM with two delta file through VDDK

ocdata — Wed, 24 Nov 2021 02:23:37 GMT

In my case, the issue was resolved by using VDDK 6.7 to backup a quiesced snapshot image on a vSphere server running 6.7. The moref snapshot field passed to *ConnectEx appears to have no effect in either 6.7 or 7.0.

topic Re: How to backup VM with two delta file through VDDK in Virtual Disk Development Kit Discussions

How to backup VM with two delta file through VDDK

quiesced snapshot part

none quiesced snapshot part

question

Re: How to backup VM with two delta file through VDDK

Re: How to backup VM with two delta file through VDDK

Re: How to backup VM with two delta file through VDDK

Re: How to backup VM with two delta file through VDDK