Transactional NTFS

Transactional NTFS (abbreviated TxF) is a component of Windows Vista and later operating systems. It brings the concept of atomic transactions to the NTFS file system, allowing Windows application developers to write file output routines that are guaranteed to either completely succeed or completely fail.

Overview

Transactional NTFS allows for files and directories to be modified, created, renamed, and deleted atomically. Using transaction ensures correctness of operation; in a series of file operations (done as a transaction), the operation will be committed if all the operations succeed. In case of any failure, the entire operation will rollback and fail.

Transactional NTFS is implemented on top of the Kernel Transaction Manager (KTM), which is a Windows kernel component first introduced in Windows Vista that provides transactioning of objects in the kernel. The NTFS file system already supports journaling of low-level operations, such as writing a block of data. Transactional NTFS expands on this capability to include:

* Atomic operations on a single file:: A common example of this is saving a file from an application; if the application or machine were to crash while writing the file, then only part of the file could be written, possibly resulting in a corrupted file. This would be a very significant problem if a previous version of the file was being over-written, as data would likely be lost.
* Atomic operations spanning multiple files:: If an application needs to update several files at once with a set of changes, all the necessary file operations can be performed as a single transaction, preventing inconsistent updates in the event of a failure.
* Atomic operations spanning multiple computers:: Performing the same operation on multiple computers is a fairly common administrative task in a corporate network; Transactional NTFS integrates with the Distributed Transaction Coordinator to ensure that the change is successfully applied to all machines.

Using Transactional NTFS for transactions on Encrypting File System files is not supported until Windows Vista Service Pack 1 (SP1) and Windows Server 2008. [cite web
url=http://msdn.microsoft.com/en-us/library/aa365738(VS.85).aspx
title=When to Use Transactional NTFS (Windows)
accessdate=2008-06-04
work=KTM Reference
publisher=Microsoft]

See also

* Features new to Windows Vista
* ACID

References

External links

* [http://blogs.msdn.com/because_we_can/ Because We Can] , a Microsoft developer blog that discusses TxF both conceptually and in code
* [http://msdn.microsoft.com/en-us/library/bb986748(VS.85).aspx Kernel Transaction Manager] documentation on the Microsoft Developer Network.