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On Microsoft Windows Server 2008 R2, the Scan and Fix dialog may be presented when adding pass-through disk to highly available virtual machine


Symptoms

Consider the following scenario: 

·         Windows Server 2008 R2 configured with Hyper-V and Failover Clustering. 

·         Failover Cluster is hosting one or more highly available virtual machines. 

·         A formatted disk, with or without a drive letter, is added to the Failover Cluster as available storage. 

·         This disk is then hot-added to the highly available virtual machine under the SCSI Controller as a pass-through disk.

When hot-adding a formatted disk to a highly available virtual machine, a dialog box with the following message may be displayed in the virtual machine.

“Do you want to scan and fix <volume name> (drive letter)?”

If the formatted disk is hot-added as a pass-through disk with a drive letter already assigned, then the dialog will be presented as soon as the disk is detected in the virtual machine.  Otherwise, the dialog will be presented when a drive letter is assigned within the virtual machine.

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Cause

A race condition occurs when the pass-through disk is being mounted in the virtual machine while be dismounted on the host.  This results in the volume being marked as dirty.

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Resolution

If the pass-through disk being added to the virtual machine has already been formatted, then the recommended action is to accept the scan and fix option on the dialog.  This will result in the dirty bit being cleared from the volume.  As an alternative, the scan and fix dialog will not be presented if the pass-through disk is unformatted when added to the virtual machine.  The disk can then be formatted from within the virtual machine.

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More Information

For more information on pass-through disks, please see the following site:

http://blogs.technet.com/b/askcore/archive/2008/10/24/configuring-pass-through-disks-in-hyper-v.aspx

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Keywords: kb

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Article Info
Article ID : 2386589
Revision : 1
Created on : 1/7/2017
Published on : 8/23/2010
Exists online : False
Views : 151