Symptoms and error messages for corrupted Hyper-V VHD files are numerous, from the VM refusing to start, to failures to attach the VHD with messages like

"Failed to open attachment 'C:\ directory \MyVHD.vhd'. Error: 'The file or directory is corrupted and unreadable.'”

There are many possible causes why your VHD may become corrupted. It is not necessary to figure out the exact cause if you need it back fast: just restore the VHD from your latest backup, or as Ben Armstrong puts it in his blogpost“Run data recovery tools inside the virtual machine."” As with all things in IT “fast” is a relative term – restoring a 500 GB disk from backup can take hours. Plan accordingly.

If you are going to take the time to investigate the cause, or do not have a backup, then you must “go all forensic”.

No mater what the VHD type, most common causes of data corruption in the VHD (whether fixed or dynamic)  are from:

• Data corruption due to faulty / failing physical storage
• Data corruption due to transferring files over faulty / failing networks

If you can trace back the chain of events leading to the corruption, you will usually find a failure either by disconnecting storage while the virtual drive was being created or moved over the network  Note that switching the disk-type from one to the other or expanding the disk may cause the problem, and, for some people, it has solved the problem. Sometimes this failure is not hardware, but caused by 3rd party encryption and anti-virus programs that have been installed on the host.

This Core Team blog post shows one way to begin your analysis.

Fixes to try:

• Mounting the vhd file to the parent partition, and then chkdsk to repair it. Ben Armstrong gives the method of mounting vhd files in his blog.
• Check for integrity using the Hyper-V. Add the vhd file to the IDE controller and then hit the Inspect button
• Merge any VHD and AVHD files. Check if you can open them through windows 7, server 2008 or WinImage (for Virtual PC and Virtual Server VHDs)
• This forum thread mentions a 3rd party  $150 tool called MediaHeal if the disk is an older OS (WinXP,WinVista,Windows2000,Windows2003,WinServer,Windows Vista Ultimate,WinNT 4)..
• Try the free Microsoft vhdtool (http://archive.msdn.microsoft.com/vhdtool) that includes  a"repair" function which is designed to undo an expand operation on a base VHD when differencing VHDs are present

"As always, be vigilant when opening any PDF attachments in unsolicited emails."

Headsup that Symantec today issued a warning of Adobe Reader Zero-day being exploited in the wild. Go smack your users and remind them what happens when you open attachments that drop backdoors on the system.

The new www.answerdesk.com service offers free support 24/7/365 with the option to upgrade to paid support right there if the free session does not suffice. *

*Currently for English-speaking customers, however some Answer Techs do speak other languages, and you can filter/select those ones if you wish.

What’s not to like? This is your get-out-of-tech-support-to-my-friends-and-family-jail-free card! Enjoy

Just sign the paper first

and then pick from the self-service menu:

1. Windows and Office – called “premium software support” ($99/hour if the free session does not work) NOTE: the “latest software": list on the website is Windows 7, Windows Vista, Windows XP, and Office applications (2010, 2007 and 2003).

2. PC optimization (the website does not distinguish or exclude server-class PCs)

3. virus removal and protection

4. one-on-one personal training

You get to select your “answer tech” based on profile information filters, such as their pics, language, service name, number of cases and rating. Curiously, “on line right now” is *not* one of the filter criteria – MSFT – you listening?

From the FAQ (http://www.answerdesk.com/support/faq.s2):

Steps:

1. Choose any one of our Answer Techs for a complimentary consult chat. You’ll be able to see whether an Answer Tech is currently online or offline. You can immediately chat with an Answer Tech who’s online, or leave a message for one whose offline. You can browse through the Answer Techs by viewing their profiles and reading about their service history and experience.
2. The Answer Tech you choose to speak with will attempt to diagnose and resolve your PC questions during a complimentary troubleshooting session. If the Answer Tech cannot resolve your problem during that time, and one of our service offers is appropriate for you, the Answer Tech will detail an offer and provide explanation of the service. If you wish to arrange a training session, any available Answer Tech can schedule a time that works with your schedule.
3. Should you choose to accept the service, you will go through the purchase process, and the Answer Tech will perform the service on the PC. The Answer Tech will use remote assistance to temporarily access your PC, with your permission, to perform the necessary actions to resolve your PC issues. Please keep in mind we currently only accept major credit cards as payment.

System Requirements:

• Broadband internet connection for remote access
• Windows XP SP1, Windows Vista, or Windows 7
• Internet Explorer 7 and higher or Mozilla Firefox 3.6 and higher
• 300 MHz or higher (processor clock speed recommended), 233 MHz minimum required (single or dual processor system)
• Intel Pentium/Celeron, or AMD K6/Athlon/Duron, or compatible processor recommended
• 256MB RAM or higher recommended (The minimum may limit performance and some features)
• SVGA (1024x768) or higher
• Recommended use of default browser security setting levels
• Macromedia Flash 8 and up

For freee training on Failover Clustering with Hyper-V: Designing a Highly-Available Infrastructure for the Private Cloud

Register here: http://mctreadiness.com/MicrosoftCareerConferenceRegistration.aspx?pid=287 

Here's what is covered:

• Introduction to Clustering – basics of Windows Server 2008 R2 Failover Clustering
• Hyper-V High-Availability – best practices, tips and tricks to provide VM high-availability and mobility
• Private Cloud High-Availability –  integration from SCVMM (2008 R2 and 2012) and multi-site clustering

Symon Perriman and Elden Christensen are your presenters. Reccomended.

Did I mention it is free?