In Windows Vista, Windows ReadyDrive does not work if the first partition of a hybrid hard disk drive has less than 32 megabytes (MB) of free space. When this problem occurs, the operating system does not recognize the hybrid hard disk drive. Instead, the operating system uses this disk drive as a traditional disk drive.

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This issue occurs because the operating system incorrectly compares the free space with the desired space.

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Hotfix information

A supported hotfix is now 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. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:Note If additional issues occur or 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. To create a separate service request, visit the following Microsoft Web site:

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Vista, x86-based versions

File name	File version	File size	Date	Time	Platform
Sysmain.dll	6.0.6000.20554	540,672	10-Mar-2007	02:50	x86
Systemsf.ebd	Not Applicable	177,772	07-Jan-2007	05:51	Not Applicable

Windows Vista, 64-bit versions

File name	File version	File size	Date	Time	Platform
Sysmain.dll	6.0.6000.20554	842,752	10-Mar-2007	04:01	x64
Systemsf.ebd	Not Applicable	456,680	07-Jan-2007	05:51	Not Applicable

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To work around this issue, make sure that the first partition of a hybrid hard disk drive has at least 32 MB of free space.

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

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A hybrid hard disk drive (H-HDD) is a new type of hard disk drive that adds flash memory to a standard mobile PC hard disk drive. By using a hybrid hard disk drive, Windows ReadyDrive provides better performance, better reliability, and longer battery life. For more information, visit the following Microsoft Web site: To determine whether the operating system recognizes the hybrid hard disk drive, follow these steps:

1.	Click Start, type Device Manager in the Start Search box, and then press ENTER.
2.	Click Continue in the User Access Control dialog box.
3.	In the Device Manager window, expand the Disk drives node, right-click the node that corresponds to your hybrid hard disk drive, and then click Properties.
4.	Determine whether the NV Cache tab is present.

Note The NV Cache tab may be absent for other reasons. It does not necessarily mean you are experiencing this problem. For example, this tab is absent if the hybrid hard disk drive has not passed the performance assessment.

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For more information about the standard terminology that is used to describe Microsoft software updates, click the following article number to view the article in the Microsoft Knowledge Base:

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