The Wiert Corner – irregular stream of stuff

Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

  • My badges

  • Twitter Updates

  • My Flickr Stream

  • Pages

  • All categories

  • Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 2,732 other followers

ESXi: shrinking a thin provisioned disk by first exploding it with zero content

Posted by jpluimers on 2020/09/07

In addition to ESXi: shrinking a Windows disk, you can shrink any ESXi thin provisioned disk by first exploding it with zero content, then shrinking it like described by [WayBack] How to Shrink a Thin VMDK on ESXi 5.0 | Boerlowie’s Blog.

It comes down to using this command:

 vmkfstools --punchzero myVirtualMachineDisk.vmdk

You can replace --punchzero with -K if you like more cryptic arguments.

This works because thin provisioned vmdk disk files are sparse files where zero content can be non-allocated.

The trick requires all empty space to be zeroed out (which usually comes down using a tool like sdelete on Windows or shred on Linux), hence the “exploding” in the post title.

For a good explanation on thin, versus thick versus eagerlyZeroedThick, read [WayBackThin Provisioning – What’s the scoop? – VMware vSphere Blog.

A few remarks:

  • this only works within datastores, so when you transfer your file out, then the file will be the thick size
  • an OVF exported virtual machine will benefit from thin provisioned disks
  • the du command will show the actual storage size (including the savings from think provisioned disks)
  • the ls command will show then “virtual” storage size (excluding any thin provisioning gains)
  • the difference between ls and du output is the thin provisioning gain

–jeroen

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

 
%d bloggers like this: