Free Up Memory for Hyper-V Guests

Mark Berry November 9, 2015

I run a small Server 2012 R2 machine that functions primarily as a Hyper-V server. It has 12 GB of RAM. The guests do not use dynamic RAM. Today I had four guests running, consuming a total of 7.5GB of RAM. I wanted to start a fifth guest that would use an extra 1 GB. That would still leave 3.5 GB physical memory free to run the host OS, which should be more than enough. But starting the VM kept failing with the message “Not enough memory in the system to start the virtual machine” (Hyper-V-Worker event ID 3122).


Write Cache Warnings on Hyper-V Guest after KB2853952

Mark Berry October 10, 2013

Starting in September 2013, Windows Server 2012 R2 machines running as Hyper-V guests started issuing these warnings on reboot:

Log Name:      System
Source:        Disk
Event ID:      32
Level:         Warning
The driver detected that the device \Device\Harddisk0\DR0 has its write cache enabled. Data corruption may occur.

Log Name:      Directory Service
Source:        Microsoft-Windows-ActiveDirectory_DomainService
Event ID:      1539
Level:         Warning
Active Directory Domain Services could not disable the software-based disk write cache on the following hard disk.
Hard disk:
Data might be lost during system failures.


Restore a Hyper-V Server to an Optiplex 960, Take 3

Mark Berry April 6, 2013

This is the third in the series of almost annual articles about my experiences testing a Hyper-V restore. I’ve done this successfully in 2011 and 2012. Why repeat? To make sure disaster recovery is still possible, and to try a new approach.


Restore a Hyper-V Server to an Optiplex 960, Take 2

Mark Berry March 12, 2012

In January 2011, I wrote about my experience restoring a Hyper-V Server to an Optiplex 960. That article is exhaustive (and exhausting). I’ve done the same test again and wanted to write up a somewhat shorter procedure. If you get stuck in this procedure, refer to the original article for details.


Can’t Ping Server after Changing Router

Mark Berry November 12, 2011

After installing a new router, I was no longer able to ping my Hyper-V server. Why not? The router sits at the edge of the network—how could it affect pinging on the local LAN?


Hyper-V Certificate Will Expire within 30 Days

Mark Berry June 18, 2011

It may be a bit sensationalistic to call it a time bomb, but apparently Hyper-V will only run for a year before the self-signed certificate that allows remote access to the machines expires. Supposedly it will auto-renew (unless you’re on Server 2008 and need this hotfix), but according to MSKB 2413735, you may still be left with an inoperable mouse and need to save/resume your VMs.


Restore a Hyper-V Server to an Optiplex 960

Mark Berry January 7, 2011

Recently I upgraded a small server to run Windows Server 2008 R2 as a Hyper-V host, with Server 2008 R2 as a guest as well. I’ve read that Windows Server Backup can restore to dissimilar hardware. That could be especially helpful in a small environment where no other servers are available. Can I restore the entire Server 2008 host and guest to an Optiplex 960 desktop? How long will it take?


Hyper-V Virtual Machine Failed to Start after Copying VHD

Mark Berry October 8, 2010

On Windows Server 2008 R2 running Hyper-V, I copied a VHD to an external drive using Windows Explorer. After compacting the drive, I copied the VHD back to its original location and tried to start the virtual machine. I got a long message telling me that the virtual machine failed to start due to an access denied error.



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