Virtual Disk(s) Locked (code 1935)


A VMware backup plan terminates with the following warning: Virtual disk(s) locked. Cannot back up VM(s): some virtual disks are locked with the list of VMs that failed to back up.


To prevent concurrent changes to critical virtual machine files and file systems, ESXi hosts establish locks on these files. In certain circumstances, these locks may not be released when the virtual machine is powered off. As such, the files cannot then be accessed by other ESXi hosts while locked and the virtual machine fails to power on.

Virtual machine files locked during runtime include:

  • VMNAME.vswp
  • DISKNAME-flat.vmdk
  • VMNAME.vmx
  • VMNAME.vmxf
  • vmware.log


Initial Quick Test

Set DRS in manual mode and attempt to power on the virtual machine on all hosts in the cluster. If the virtual machine powers on, that host helps the lock.

Identify the Locked File

  1. Power on the virtual machine, this process should fail and display an error message. Make note of this error.
  2. Connect to the ESXi host the virtual machine is on with an SSH session.
  3. Find the IP address of the host holding the lock by running vmfsfilelockinfo on the VMDK flat, delta, or SEsparse file for VMFS, or the .UUID.lck file for vSAN.

vmfsfilelockinfo takes these parameters:

  • File to be tested
  • Username and password for accessing VMware vCenter Server (when tracing MAC address to ESX host.)

For example:

vmfsfilelockinfo -p /vmfs/volumes/iscsi-lefthand-2/VM1/VM1_1-000001-delta.vmdk -v -u administrator@vsphere.local

vmfsflelockinfo Version 1.0
Looking for lock owners on "VM1_1-000001-delta.vmdk"
"VM1_1-000001-delta.vmdk" is locked in Exclusive mode by host having mac address ['xx:xx:xx:xx:xx:xx']
Trying to make use of Fault Domain Manager
Found 0 ESX hosts using Fault Domain Manager.
Could not get information from Fault domain manager
Connecting to with user administrator@vsphere.local
Password: xXxXxXxXxXx
Found 3 ESX hosts from Virtual Center Server.
Searching on Host
Searching on Host
Searching on Host
MAC Address : xx:xx:xx:xx:xx:xx

Host owning the lock on the vmdk is, lockMode : Exclusive

Total time taken : 0.27 seconds.

During the lifecycle of a powered on virtual machine, several of its files transitions between various legitimate lock states. The lock state mode indicates the type of lock that is on the file. The list of lock modes is:

  • mode 0 = no lock
  • mode 1 = is an exclusive lock (vmx file of a powered on virtual machine, the currently used disk (flat or delta), *vswp, and so on.)
  • mode 2 = is a read-only lock (For example on the ..-flat.vmdk of a running virtual machine with snapshots)
  • mode 3 = is a multi-writer lock (For example used for MSCS clusters disks or FT VMs)
  1. To find the name of the process holding the lock, run lsof 'locked_file_name' on the host holding the lock and filter the output for the file name in question:

For example:

lsof | egrep 'Cartel|VM1_1-000001-delta.vmdk'

Cartel | World name | Type | fd | Description
36202 vmx FILE 80 /vmfs/volumes/556ce175-7f7bed3f-eb72-000c2998c47d/VM1/VM1_1-000001-delta.vmdk

This shows that the file is locked by a virtual machine having Cartel ID 36202.

  1. Now display the list of active Cartel IDs by with this command:
esxcli vm process list

This displays information for active virtual machines grouped by virtual machine name and having a format similar to:

World ID: 36205
Process ID: 0
VMX Cartel ID: 36202
UUID: 56 4d bd a1 1d 10 98 0f-c1 41 85 ea a9 dc 9f bf
Display Name: Alternate_VM27
Config File: /vmfs/volumes/556ce175-7f7bed3f-eb72-000c2998c47d/Alternate_VM27/Alternate_VM27.vmx

The virtual machine entry having VMX Cartel ID: 36202 shows the display name of the virtual machine holding the lock on file VM1_1-000001-delta.vmdk, which in this example, is Alternate_VM27.

  1. If no processes are shown, the following script can search for VMs with the locked vmdk mounted.
for i in $(vim-cmd vmsvc/getallvms | grep -v Vmid | awk -F "/"  '{print $2}' | awk '{print $1}'); do echo $i && find ./ -iname $i | xargs grep vmdk | grep -Ei VMDKS_TO_LOOK_FOR ; done

Remove the Lock

  1. Power off the virtual machine holding the lock.
  2. Reboot the ESXi host that holds the lock.