Symptoms

When you deploy Microsoft Exchange Server 2013 on Resilient File System (ReFS) volumes on computers that are running Windows Server 2012, Exchange databases become heavily fragmented. Therefore, end-users experience poor performance on Exchange-related operations. For example, it takes longer than expected to change a view in Outlook Web Access. 

Cause

This issue occurs because a large file is broken into small chunks during the allocation request. In an Exchange database, a large file is extended in large chunks, such as 128 megabyte (MB) chunks or 256 MB chunks. This issue occurs when another thread that does transactional logging requests allocations in smaller sizes at the same time.

Therefore, when a 128 MB file allocation request is received, the medium allocator requires space from the large allocator. However, some space is allocated to a small allocation request (such as log file allocation request) at the same time. In this situation, the large file is prevented from contiguous allocation. This behavior results in fragmentation.

Note ReFS uses a hierarchical allocator to manage disk space allocation. There are large, medium and small allocators that differ in the granularity of space they manage. Each allocator requests space from its parent allocator. For example, a medium allocator manages medium-sized chunks that are allocated from the large allocator. At the default setting, the medium allocator requests space from the large allocator in 64 MB chunks.

Resolution

This hotfix is also available at Microsoft Update Catalog.

Hotfix information

A supported hotfix is available from Microsoft. 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 this specific problem.

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, submit a request to 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, visit the following Microsoft website:

http://support.microsoft.com/contactus/?ws=supportNote 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 hotfix, you must be running Windows Server 2012.

Registry information

To use the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

The global 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 file information notesImportant Windows 8 hotfixes and Windows Server 2012 hotfixes are included in the same packages. However, only "Windows 8" 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" 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

    6.2.920 0.20 xxx

    Windows Server 2012

    RTM

    LDR

  • 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 Server 2012" 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.

For all supported x64-based versions of Windows Server 2012

File name

File version

File size

Date

Time

Platform

Refs.sys

6.2.9200.20727

845,568

24-May-2013

02:09

x64




Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional file information for Windows Server 2012

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

File name

Amd64_e154abeca50be7e1ec802a11df84a249_31bf3856ad364e35_6.2.9200.20727_none_2dbd5fa1ef8c315d.manifest

File version

Not applicable

File size

696

Date (UTC)

24-May-2013

Time (UTC)

15:15

Platform

Not applicable

File name

Amd64_microsoft-windows-refs_31bf3856ad364e35_6.2.9200.20727_none_000daae4bf94f015.manifest

File version

Not applicable

File size

3,960

Date (UTC)

24-May-2013

Time (UTC)

02:16

Platform

Not applicable


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