Azure Hybrid & Cloud Migration Blog

Article by: Zahir Hussain Shah
zahirshahblog.com

Category: Exchange 2010 VMs on Hyper-V Servers are stopped due to unavailability of free disk space, Hyper-V, Exchange 2010 Virtualization over Hyper-V, VSS Shadow Copies

Hyper-V Server local storage filled up with hidden data | Hyper-V Server local disk is getting fill automatically

Problem Description:

Writing this article is quite of interesting for me, because the problem and its corresponding solution, which Im going to explain here is self quite interesting in nature J, so lets start, let me first tell you what problem I faced, we are running our Exchange 2010 SP 1 environment on Hyper-V Windows Server 2008 R2 Servers, we have two Hyper-V nodes on which we distributed both two roles equally, means 1 HUB/CAS and 1 Mailbox on one Hyper-V node, and another HUB/CAS and Mailbox is on second Hyper-V Node, where each VM contains two virtual hard disk (Fixed Disk), and as you know that Fixed Disk never grows, and while these VMs were running from past one and half months, we started observing that local disk space where these VMs are stored, started running out of FREE DISK SPACE (D:\ Drive), and which started alarming in my brain, because if the free disk space goes finish your VM will be stopped, and during this time, I saw that the VM folders are not growing, but free disk space insdie the D:\ drive (Physical Disk of Hyper-V Server) is getting filled up, so what is eating up my all disk space ?

Note: If you have VMs snapshot is configured then, you have to look in to the other side which is snapshot, because snapshot grows, and VHD remains constant, and it is always recommended not to take snapshot of Production systems.

Problem statement:
Hyper-V VMs are folder size remains same by free disk space of physical disk of Hyper-V Server gets filled up.

Cause:
So as I mentioned that VM folder remains same, but there is some hidden data which taking all the disk space, so let me tell you the actual culprit of this cause, which is Volume Shadow Copies, and by default since only SYSTEM has NTFS permission on these System generated Volume Shadow Copies, you will see their size 0 KB, but in actuality, they are taking all of your disk space, so if you want to see them, do the following:

1) Go to folder option and show all the hidden items including system files
2) Go to the System Volume Information and take the properties
3) Go to Security, Advance and in the Ownership, take the ownership and add your user account in the NTFS permission tab and give full permission.
4) After taking ownership and giving full permission on System Volume Information folder, take the properties again and now you can see that all the consumed free disk space is taken by these system generated files.

Solution:
For bring this consumed free disk space, lets do the following for removing these Volume Shadow copies:

1) Open CMD with RUN AS ADMINISTRATOR
2) First list the available generated shadow copies by running the below command:

DISKSHADOW

Since now you are on DISKSHADOW prompt at command prompt, lets list all the available shadow copies by running the below command from the DISKSHADOW prompt:

LIST SHADOWS ALL

Upon running the LIST SHADOWS ALL command, you will see all the shadow copies, so then you can run the below command from the same DISKSHADOW command prompt for deleting these shadow copies:

DELETE SHADOWS ALL

And now you can go back to Windows Explorer, and can evaluate your available free disk space, and will glad to see that all your hidden consumed disk space is back now J

I hope this will resolve your problem, and will help to stay relax from being tense to see your Hyper-V Servers (or any Server) physical disk free space getting consumed by hidden stuff.

Cheers!

Zahir Hussain Shah
Infrastructure Practice Consultant – Unified Communications
MCSE, MCTS, MCTIP Enterprise Administrator, ITIL
Blog: http://zahirshahblog.com | LinkedIn | Twitter