FBWF API Functions (Standard 7 SP1)

7/8/2014

The following table describes the FBWF functions that are used to manage the system-wide write cache.

Function	Description
FbwfEnableFilter	Enables write filtering in the next session.
FbwfDisableFilter	Disables write filtering for the next session.
FbwfIsFilterEnabled	Queries the filter state for the current and next station.
FbwfSetCacheThresholdEx	Sets the size of the overlay threshold.
FbwfCacheThresholdNotification	Signals an event when the available write cache falls below a specified size.
FbwfInitializeNotifications	Starts the worker thread that sends cache threshold notifications.
FbwfUninitializeNotifications	Stops the worker thread that sends cache threshold notifications.
FbwfEnableCachePreAllocation	Causes the write filter to allocate the entire cache size at startup instead of allocating memory as needed.
FbwfDisableCachePreAllocation	Turns off cache pre-allocation so that cache memory is allocated only as needed.
FbwfGetMemoryUsageEx	Returns the total memory size used for directory structure and file data by the filter driver.
FbwfEnableCompression	Enables the write filter to compress the memory cache.
FbwfDisableCompression	Disables cache compression.
FbwfIsCompressionEnabled	Retrieves the status of the compression flag.

The following table shows the functions that are used to manage the protection of a specific volume.

Function	Description
FbwfProtectVolume	Enables write protection for a specified volume.
FbwfUnprotectVolume	Removes write protection for the specified volume.
FbwfGetVolumeList	Retrieves the list of protected volumes.
FbwfIsVolumeProtected	Retrieves the protected status for a specified volume in both the current and next sessions.
FbwfFindFirstEx	Returns the first entry of the files and folders that are currently cached by the write filter.
FbwfFindNextEx	Returns the next entry of files and folders that are currently cached by the write filter.
FbwfFindCloseEx	Closes the cache detail search for previous FbwfFindFirstEx and FbwfFindNextEx calls.

The following table shows the functions that are used to manage files excluded within a protected volume.

Function	Description
FbwfAddExclusion	Adds a file or directory to the exclusion list.
FbwfRemoveExclusion	Removes a file or directory from the exclusion list.
FbwfGetExclusionList	Retrieves the list of files and directories in the exclusion list.

The following table shows the functions that are used for file commit and restore.

Function	Description
FbwfCommitFile	Writes the cached file overlay to the physical disk file.
FbwfRestoreFile	Clears the cached view of the specified file.

The following table shows the functions that are used for disk size queries.

Function	Description
FbwfGetSizeDisplay	Returns the size display mode for the current and next session.
FbwfSetSizeDisplay	Sets the size display mode for the next session.
FbwfGetVirtualSize	Returns the structure FbwfFSInfo that contains volume sector size information in virtual numbers.
FbwfGetActualSize	Returns the structure FbwfFSInfo that contains volume sector size information in actual numbers.

The following table shows the File-Based Write Filter (FBWF) API functions that are deprecated in Windows Embedded Standard 7.

Note

These APIs can handle cache up to 4GB.

Function	Description
FbwfFindClose	Deprecated. Closes the FbwfFindFirst/FbwfFindNext search.
FbwfFindFirst	Deprecated. Retrieves information about the first file in the FBWF memory cache.
FbwfFindNext	Deprecated. Retrieves information about the next file in the FBWF memory cache.
FbwfGetMemoryUsage	Deprecated. Retrieves information about memory currently used by the cache.
FbwfSetCacheThreshold	Deprecated. Sets the maximum amount of RAM the write cache may use.

See Also