Reclaim unused space from VMDK

Let’s say you have a bunch of servers *Cough Server 2008 R2* that have been fairly well maintained and all running on VMware’s ESXi hypervisor system. As a regular server admin you’ve come to terms with updates and keeping systems for the most part on the latest n greatest. Now lets also say you happen to be the storage admin as well and you find you are running out of space on your SAN. What do you do? Usually buy more space. But lets get to the real heart of the matter… Systems, if not properly set up, get messy (don’t get me started on Windows registry.) we’re sticking with storage as the topic of the day. Well good news is I’m here to help you reorganize and re-claim all that space. Lets get started!

*NOTE* if you are running thick provisioned discs you’ll have to svmotion them to another datastore to convert them to thin first.

First and foremost you’re going to want to clean up your WINSXS folder. Don’t believe me, run windirstat to find out just how big it has become from all those updates.

How do you clean up your WINSXS? You may ask well, first ensure your server has Windows6.1-KB2852386-v2-x64 installed. Note these steps work for Windows 7 as well if anyone happens to need to save space on a client machine. You might be able to find cleanmgr.exe online, but your safer to copy it from another server. or try this. run cleanmgr.exe make sure you run it as an administrator and clean system files. Clean up the old update files. Reboot (Your HAVE to reboot to complete the update removals before moving to the next step!)

For the next part you may or may not want to do depending on what the app reports. Run Disk Defrag. In this case my servers were about %40 fragged; meaning that over time as files were added, used,and then deleted they were placed randomly throughout the disk depending on where the FAT (File Allocation Table) generally in this case NTFS telling which sections were free to overwrite. Yup when you delete a file it’s not actually deleted from the sections just from the table. So Defragging pretty much “shoves” all the actually still in use data nice and organized at the “front” of the disc. This is generally only required on spindle discs, if your system is using SSD, or a logical unit based on RAID this won’t matter.

Now if you’re simply clearing space on a phsyical device, barebone device. You’re pretty much good to go. However for the rest of us virtulaized guys who want to reclaim space on our SAN’s we still have a ways to go.

This is where I find the “fun” begins. if you attempt to look it up you’ll find some old articles from VMware about using vmware tools. Well #1) The GUI options are gone,if you attempt to find vmware tools under control panel, you won’t find it. #2) If you go ahead and try to use the cmdlets you’ll probably find it simply returns the disc can’t be shrunk. I personally say don’t waste your time attempting to do anything here with VMware tools. For Linux users you can accomplish this via dd very easily. For the rest of us Windows users we can thank the Great Mark Russinovic for sysinternals, in particular this time for sdelete. Grab it and run sdelete -z (important in v1.56 it was -c, in 1.61 use -z) If you don’t specify a drive it will use the drive you run the cmd from, I’m assuming.

Time for the last and final fun part. Read this and this. Once you’ve done that I’ll provide my findings:

1) You have to svmotion between datastore of different blocksizes (I found the 2 MB block size was the one that worked for me)

2) you can’t use the vmkstools holepunch option against a VMDK stored on a NFS datastore

To Paraphrase to solution:

1) Remove and delete temp files, unused profiles, and old update files.
2) Defrag to organize all the blockson the guest file system.
3) Use sdelete or dd to zero dirty blocks.
4) Hole punch or svmotion the VMDK to shrink used size.
5) Enjoy a beer and a bunch of recovered space.
6) You might even notice a performance increase from all the organized guest file systems

Jan 2018 Updates

2016 didn’t have many posts, but they sure are good ones, I forgot all about this stuff. haha.