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The files that make a VMware Virtual Machine May 16, 2012

Posted by vbry21 in VMware blogs.

In a previous article I put forward the opinion that a Virtual Machine is just a load of files, but what are those files?

A configuration file .VMX

The configuration file if we had a look inside it would list quite a bit of information related to the virtual hardware and associations to the other  files that go to make a Virtual machine, some examples of the information contained include, the MAC address for the virtual NICs, the amount of RAM associated with the VM and the serial/parallel port information and other hardware information.

Swap Files .VSWP

The swap files only exist when the VM is powered up and is only used when a host exhausts all of its allocated memory. By default the size of the file is equal in size to the amount odf memory assigned to the VM.


This is a file which is similar to the bios chip associated with a physical server or PC, This file allows us to press the F2 at VM boot and alter the hardware configuration, such as boot order of the virtual devices.

LOG files .LOG

These files contain information related logging and can be useful for troubleshooting, you may see multiple log files, but the current file is always called vmware.log

Virtual Disk Files .VMDK

A VM may have multiple .VMDK files, we’ll have the .VMDK (the disk descriptor file), a –FLAT.VMDK (where the data goes), a –DELTA.VMDK (associated with snapshots) and a –RDM.VMDK (associated with pass though disk, or a Raw Device Mapping.

Suspend State File .VMSS

Think of this of the equivalent of sticking your laptop into hibernation, when we suspend a VM the memory contents is saved to this file.

Snapshot Data File .VMSD

This file maintains information about all the snapshots that belong to the virtual machine.

Snapshot Memory State File .VMSN

This file contains the memory state of the VM at the time the snapshot was taken and will be the size of the VMs RAM, so if a VM has 8GB of RAM then the file will be 8GB.

Template File .VMTX

If the VM is a template it will have a .VMTX file instead of the .VMX file.

Few!!!!! Loads of files but all are really essential.




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