A SQL Server that is running in a Hyper-V virtual machine takes a long time to restore a database to a dynamic VHD

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Symptoms

It may take a very long time for a Microsoft SQL Server that is running in a Hyper-V virtual machine to restore a database to a dynamic virtual hard disk (VHD). This problem occurs when the virtual machine is located in a SMB Scale-Out File Server (SOFS) based Windows Server 2012 R2 cluster.

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Cause

This problem occurs because of serialization of I/O requests on dynamic VHDs.

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Resolution

Hotfix information

A supported hotfix is available from Microsoft Support. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, go to the following Microsoft website:

http://support.microsoft.com/contactus/?ws=support

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this update, you must first have update 2919355 installed in Windows Server 2012 R2.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any previously released hotfix.

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File information

The English (United States) version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows Server 2012 R2 file information and notes

Important Windows 8.1 and Windows Server 2012 R2 hotfixes are included in the same packages. However, only "Windows 8.1" is listed on the Hotfix Request page. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 8.1" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

The files that apply to a specific product, milestone (RTM,SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table.

Version Product Milestone Service branch
6.3.960 0.17 xxx Windows Server 2012 R2 RTM GDR
The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows 8.1 and Windows Server 2012 R2" section. MUM and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

Version	Product	Milestone	Service branch
6.3.960 0.17 xxx	Windows Server 2012 R2	RTM	GDR

For all supported x64-based versions of Windows Server 2012 R2

File name	File version	File size	Date	Time	Platform
Csvflt.sys	6.3.9600.17669	214,016	29-Jan-2015	03:00	x64
Csvfs.sys	6.3.9600.17669	669,696	29-Jan-2015	02:59	x64
Ntfs.sys	6.3.9600.17669	2,022,720	29-Jan-2015	21:08	x64
Refs.sys	6.3.9600.17669	922,432	29-Jan-2015	21:08	x64

Additional file information for Windows Server 2012 R2

Additional files for all supported x64-based versions of Windows Server 2012 R2

File name	Amd64_69285ab84fa66ea241115f2ed08ceec9_31bf3856ad364e35_6.3.9600.17669_none_9f8632d4c4946db6.manifest
File version	Not Applicable
File size	696
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Amd64_6b221462cb1d8c0737239c3d90f9e37b_31bf3856ad364e35_6.3.9600.17669_none_2856ee8abce734f6.manifest
File version	Not Applicable
File size	696
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Amd64_cf7cd59c32357769f5a766bd126ddb7c_31bf3856ad364e35_6.3.9600.17669_none_255780d803d70a94.manifest
File version	Not Applicable
File size	718
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Amd64_e47b2cd4c498ba644de4ef7c49a870b7_31bf3856ad364e35_6.3.9600.17669_none_a040e2d3b5dff3d2.manifest
File version	Not Applicable
File size	719
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Amd64_microsoft-windows-f..cluster-csvflt-core_31bf3856ad364e35_6.3.9600.17669_none_addbfec68b87ab1a.manifest
File version	Not Applicable
File size	4,685
Date (UTC)	29-Jan-2015
Time (UTC)	04:10

File name	Amd64_microsoft-windows-f..rcluster-csvfs-core_31bf3856ad364e35_6.3.9600.17669_none_c70fc67e3350269d.manifest
File version	Not Applicable
File size	3,087
Date (UTC)	29-Jan-2015
Time (UTC)	04:10

File name	Amd64_microsoft-windows-ntfs_31bf3856ad364e35_6.3.9600.17669_none_974a19fbf0cdf7ee.manifest
File version	Not Applicable
File size	16,014
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Amd64_microsoft-windows-refs_31bf3856ad364e35_6.3.9600.17669_none_974f70dbf0c8dcdb.manifest
File version	Not Applicable
File size	6,021
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Package_1_for_kb2970653~31bf3856ad364e35~amd64~~6.3.1.0.mum
File version	Not Applicable
File size	1,837
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Package_2_for_kb2970653~31bf3856ad364e35~amd64~~6.3.1.0.mum
File version	Not Applicable
File size	1,820
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Package_3_for_kb2970653~31bf3856ad364e35~amd64~~6.3.1.0.mum
File version	Not Applicable
File size	2,289
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Package_4_for_kb2970653~31bf3856ad364e35~amd64~~6.3.1.0.mum
File version	Not Applicable
File size	2,285
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Package_5_for_kb2970653~31bf3856ad364e35~amd64~~6.3.1.0.mum
File version	Not Applicable
File size	2,538
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Package_6_for_kb2970653~31bf3856ad364e35~amd64~~6.3.1.0.mum
File version	Not Applicable
File size	1,837
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Package_for_kb2970653_rtm_gm~31bf3856ad364e35~amd64~~6.3.1.0.mum
File version	Not Applicable
File size	2,807
Date (UTC)	29-Jan-2015
Time (UTC)	21:16

File name	Package_for_kb2970653_rtm~31bf3856ad364e35~amd64~~6.3.1.0.mum
File version	Not Applicable
File size	1,485
Date (UTC)	29-Jan-2015
Time (UTC)	21:16