Home > Work related > How to extend your NTFS partition with a vmdk file on ESXi

How to extend your NTFS partition with a vmdk file on ESXi


If you are using a large windows file server on your VMware server you will probably end up with a low disk space warning one day. You could choose to resize a partition in-place there but if something goes wrong you are kinda hosed unless you have a backup. You could copy it but not everyone has that kind of disk space so I like to add an ISCSI datastore to my ESXi server and choose to copy the VM to another datastore first. Then I can try to extend the copied vmdk file using a helper vm. It required a combination of stopping the vm, copying the file, renaming the original vm and bringing the new extended vmdk file online to extend it. Once I verify that everything was working our plan was to then remove the old VM once we were completely sure it was working and to free up the space for other projects.

In ESXi vsphere Shutdown vm

Login to ESXi server using putty

cp /vmfs/volumes/datastore1/WindowsXP /vmfs/volumes/datastore2


Here we see the copied file is exactly the same at the original

In ESXi vsphere

Rename Old VM to .old (this changes the VM name not the directory name)


Open helper vm and edit settings, close

Open settings again and increase the hard drive to desired size

Attach copied vmdk file from new datastore directory to existing VM as another drive

In helper OS

Open command prompt and type diskpart

List volume


Select volume (new volume number)



In ESXi vsphere

Create new VM (custom) with old name and do not attach hard drive

Add hard drive and use existing vmdk from new datastore directory


When you boot the machine it might do a check disk to resize the partition or after it boots it might need to restart with the new device added.

Verify IP address assignments make changes after initial boot if you do not assign IP automatically using static DHCP addressing.

Reboot and verify operation and once you are satisfied to can delete the old VM.

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