vVol -- Cannot power on VM -- Error "Cannot open the disk"
Article ID: 389403
Updated On:
Products
Issue/Introduction
A VM with Disks located on vVol Storage cannot be powered on. One or more of the following errors are observed:
Cannot open the disk 'vvol://#################################/rfc####.########-####-####-####-###########/#####.vmdk; or one of the snapshot disk it depends on.
cat /vmfs/volumes/vvol:1234567890A123456789A01234567890A/rfc123.12345678-1234-123b-1234-123456789000/DiskABCD.vmdk
RW 133143986176 VMFS "vvol://1234567890A123456789A01234567890A/rfc1111.ab1234aa-bb12-1234-1234-9876543abcd"
- Meta vVol ID UUID associated with the affected vmdk: rfc1111.ab1234aa-bb12-1234-1234-9876543abcd
- vmdk size: 133143986176
VMware.log reports following error for the vmdk:
2025-02-13T22:39:36.177Z In(05) worker-2689414 - DISK: OPEN scsi2:0 '/vmfs/volumes/vvol:1234567890A123456789A01234567890A/rfc123.12345678-1234-123b-1234-123456789000/DiskABCD.vmdk' persistent R[]
2025-02-13T22:39:36.183Z In(05) worker-2689414 - DISKLIB-VMFS : VmfsExtentCommonOpen: possible extent truncation (?) realSize is 67108864, size in descriptor 133143986176.
2025-02-13T22:39:36.184Z In(05) worker-2689414 - DISKLIB-LIB : Failed to open '/vmfs/volumes/vvol:1234567890A123456789A01234567890A/rfc123.12345678-1234-123b-1234-123456789000/DiskABCD.vmdk' with flags 0x4a The file specified is not a virtual disk (15).
2025-02-13T22:39:36.184Z In(05) worker-2689414 - DISKLIB-VMFS : "vvol://1234567890A123456789A01234567890A/rfc1111.ab1234aa-bb12-1234-1234-9876543abcd" : failed to open (The file specified is not a virtual disk): Size of extent in descriptor file larger than real size. Type 3
2025-02-13T22:39:36.217Z In(05)+ vmx - Cannot open the disk '/vmfs/volumes/vvol:1234567890A123456789A01234567890A/rfc123.12345678-1234-123b-1234-123456789000/DiskABCD.vmdk' or one of the snapshot disks it depends on.
2025-02-13T22:39:36.217Z In(05)+ vmx - Power on failure messages: The file specified is not a virtual disk
2025-02-13T22:39:36.228Z Wa(03) vmx - VMX has left the building: 0.
Environment
ESXi 7.x
ESXi 8.x
Cause
2025-02-13T22:39:36.184Z In(05) worker-2689414 - DISKLIB-VMFS : "vvol://1234567890A123456789A01234567890A/rfc1111.ab1234aa-bb12-1234-1234-9876543abcd" : failed to open (The file specified is not a virtual disk): Size of extent in descriptor file larger than real size. Type 3
This means that from a vSphere perspective, we notice that while the known size listed in the vmdk is 133143986176, the reported size coming from Storage Array is only a fraction of it (= 67108864).
Due to this discrepancy the VM is not powering on.
In order to have a successful power on, the reported size in vSphere and the size coming from Storage Array need to be identical.
Resolution
Size discrepancy reported is huge:
133143986176 - 67108864 = 133076877312 sectors = 61.9 TB
Involve storage vendor to investigate the size discrepancy reported in VMware.log. Validate the size reported for VVOL UUID on the array.
Additional Information
If the size discrepancy is not huge, like in this example:
2025-10-07T14:34:35.822Z In(05) worker-24719422 - DISKLIB-VMFS : VmfsExtentCommonOpen: possible extent truncation (?) realSize is 2422362112, size in descriptor 2424307712. <<<========== Size reported in vmdk descriptor file is larger by 950 MB compared to size reported by array.
Work Around:
Sync the vmdk size by increasing it with a small amount.
Feedback
