Changes to Existing Features

Item
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Description
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FAT32 on DVD-RAM
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DVD-RAM disks can appear as both CD-ROM/DVD-ROM devices and as rewritable disks (like MO disks). Windows XP allows DVD-RAM media in DVD-RAM drives to be formatted and used with the FAT32 file system.
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Defragmentation APIs
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Since NT 4.0, the Windows NT file systems have exposed APIs which allow a user-mode application to query the allocated ranges of files on disk, and optimize file arrangements in order to defragment (or carefully fragment) files in order to minimize seeks while processing file I/O.
In Windows 2000 these APIs have a number of limitations. For example, they do not function on the MFT, the PageFile, or NTFS Attributes.
The feature set in Windows XP changes the behavior on NTFS as follows:
The defrag APIs no longer defragment data via the system cache. This means Encrypted files no longer need to be opened with read access.
NTFS now defragments at the cluster boundary for non-compressed files. In Windows 2000 RTM, this was limited to the page granularity for non-compressed files.
NTFS now defragments the MFT. In Windows 2000 RTM, defragmentation of the MFT was not allowed. In Windows XP, defragmentation of the MFT is performed through the regular code path, so there is no limit to how much of the MFT can be defragmented at once, and any part of the MFT can be moved except for the first 0x10 clusters. If there is no available space in the MFT to describe the change then it will be rejected. The API can move an MFT segment even if a file with its File Entry in that section is currently open.
NTFS now defragments for cluster sizes greater than 4 KB.
NTFS now defragments: Reparse points, bitmaps, and attribute lists. These can now be opened for file read attributes, and synchronize. The files are named using the regular syntax (file:name:type), so, for example foo:$i30:$INDEX_ALLOCATION or foo::$DATA or foo::$REPARSE_POINT or foo::$ATTRIBUTE_LIST.
NTFS's QueryBitmap FSCTL now returns results on a byte boundary rather than page boundary.
NTFS now defragments all parts of a stream up to and including the allocation size. In Windows 2000 RTM it was not possible to defrag the file tail between VDL and EOF.
You can now defrag into or out of the MFT Zone. The MFT Zone is now just an NTFS-internal hint for the NTFS allocation engine.
To defragment a file, the Win32 open mode needs only to have FILE_READ_ATTRIBUTES | SYNCHRONIZE.
It is possible to Pin an NTFS file so that it may not be defragged using FSCTL_MOVE_FILE. This is done by calling FSCTL_MARK_HANDLE and passing MARK_HANDLE_PROTECT_CLUSTERS as an argument. This stays in effect until the handle is closed.
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Large Files
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Windows XP (and Windows 2000 Service Pack 2) are able to create sections on arbitrarily large mapped files. The constraint that had existed in earlier versions of the memory manager (creating Prototype Page Table entries for all pages in the section) does not apply since the Windows XP memory manager can reuse PPTEs for any parts of a section that do not have a mapped view.
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Verifiers
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There are new verifier levels in addition to a new deadlock verifier. For more information, see http://www.microsoft.com/whdc/DevTools/tools/DrvVerifier.mspx
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Read-Only NTFS
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NTFS now mounts read-only on an underlying read-only volume. If the volume requires a log restart or a chkdsk, the mount will fail.
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New flag: FILE_READ_ONLY_VOLUME
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The Microsoft Win32 GetVolumeInformation function now returns FILE_READ_ONLY_VOLUME for read-only volumes. This flag is documented in the Windows XP Platform SDK.
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RSS on MO media
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The Remote Storage Services feature provided only Hierarchical Storage Management with tape as second-tier in Windows 2000. In Windows XP, RSS also supports jukeboxes with certain types of rewritable optical disks, such as Magneto-Optical (MO) disks.
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EFS Interoperability
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The Client Side Caching database can now be encrypted.
As of Windows XP Beta 1, encrypted files cannot be replicated using FRS, or backed up using snapshots. Both of these issues were resolved for Windows XP Beta 2 and later.
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Default NTFS ACL
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The default ACL on NTFS volumes has been strengthened.
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