Storage

NTFS

• Self Healing
  NTFS in Windows Vista and Windows Server 2008 includes technologies that enable on-the-fly detection and repair of file system corruptions. This self healing behavior provides increased system availability and reliability by mitigating the need to conduct offline scans and recovery. Application crashes or other unexpected behaviors caused by corrupted metadata or system files can be avoided or reduced to one-time occurrences instead of repeated occurrences due to detection of the problem files and automatically replacing them with uncorrupted backups. Authorized users may monitor and set the self healing state of volumes, initiate repair operations, and receive progress information about such operations via the fsutil repair command context.
  
  
• Symbolic Links
  NTFS in Windows Vista and Windows Server 2008 includes support for symbolic links for files and directories. Symbolic links (sometimes referred to as symlinks or soft links) are implemented using reparse points. Unlike junctions, symbolic links are always evaluated on the client system, whereas junctions are evaluated on the server. Symbolic links can be created using absolute or relative paths, though only absolute links may span volumes. The target files or directories for symbolic links can be located on local or remote systems. SMB 2.0 supports symbolic links so they may be used in networked scenarios. Possible link types include the following:
  
  
  • Local Link to a Local Target
    
    
  • Local Link to a Remote Target
    
    
  • Remote Link to Remote Target
    
    
  • Remote Link to Local Target
    

For security, only local source symbolic links are enabled by default, and only Administrators may create symbolic links by default. Both of these defaults can be changed. Evaluation of remote source symbolic links can be enabled through the Group Policy editor (gpedit.msc) under Computer Configuration | Administrative Templates | System | NTFS File System | Selectively allow the evaluation of a symbolic link, or via the fsutil behavior command context. Symbolic link creation privileges may be assigned to other users or groups via the Security Policy editor (secpol.msc) under Local Policies | User Rights Assignment | Create symbolic links.

• Large Sector Support
  Hard drives have historically been designed with physical sector sizes of 512 bytes. This will soon not always be true as the storage industry transitions to hard drive designs with larger physical sectors (usually ranging form 1 to 4 kilobytes in size) that are multiples of 512 bytes. The larger sector designs allow for enhanced data protection and correction algorithms for increased data reliability and enable greater format efficiencies that free up space for additional user data. In initial designs, 512 byte logical sectors are exposed for backwards compatibility with hardware and software that cannot address larger logical sectors. Windows 2000, XP, and Server 2003 support large logical sector drives as data disks, but cannot boot from them. NTFS and related components in Windows Vista and Windows Server 2008 include support for large logical sector hard drives as both boot and data disks. BIOS support is also required for the large logical sector boot disk scenario. The Big Sector technology consortium, of which Microsoft is a member, was formed to support the industry in transitioning to large sector hard drives.
  
  
• Transactional NTFS (TxF) / Transactional Registry (TxR)
  With the inclusion of the Kernel Transaction Manager (KTM), full ACID transactional semantics are now a fundamental part of the Windows platform. Transactional NTFS and Transactional Registry technologies in Windows Vista and Windows Server 2008 work with the KTM to allow file and registry operations to be performed in a transaction, preserving data integrity, isolating changes, and reliably handling error conditions. These operations can be local or distributed, and ISVs and administrators can also integrate transaction support into their applications. NTFS transactions can be monitored via the fsutil transaction command context.
  

Common Log File System
First introduced in Windows Server 2003 R2, the Common Log File System (CLFS) API provides high-performance, general-purpose file log services that dedicated client applications can use, and multiple clients can share to optimize log access. Any user-mode application that needs logging or recovery support can use CLFS. The Common Log File System (CLFS) saves log records in a sequential order, and can ensure that the flushed log records are preserved even after a system failure.　

Image Mastering API (IMAPI) version 2.0
IMAPI enables applications to stage and burn images to CD and DVD optical storage media and other media that lay images in the same manner. IMAPI version 2 is a complete redesign, that moves the API to user mode, supports simultaneous recording to multiple drives, provides a more extensible architecture allowing developers to create their own media formats and file systems, and includes simplified, scriptable interfaces. IMAPI version 1.0 interfaces now map to the version 2.0 interfaces. 

UDF
UDF is a file system that is defined by the Optical Storage Technology Association (OSTA). UDF is compliant with ISO-13346/ECMA-167 and is the successor to the CD-ROM file system (CDFS or ISO-9660). The UDF format supports a number of advanced features including long and Unicode filenames, access control lists (ACL)s, alternate data streams, 64-bit file sizes, sparse files, and writing to many different types of media. Windows has included read-only support for various versions of the UDF standard since Windows 98. The UDF file system driver in previous versions of Windows does not support ACLs or alternate data streams. Windows Vista and Windows Server 2008 add read/write support for versions of UDF up to UDF 2.50, read-only support for the latest version, 2.60, and support for alternate data streams. Frequent updates to the Windows optical stack are planned. 

Previous Versions
Previous Versions is a technology in Windows Vista and Windows Server 2008 that enables users to quickly recover from accidental changes or deletions of files and folders. Previous Versions is based on Volume Shadow Copy technology which first appeared in Windows Server 2003. Previous Versions automatically creates incremental copies of files and folders as you work, and enables users to restore copies made at previous points in time to recover from current mistakes. 

 

Windows SuperFetch
Historically, memory management systems have used a process known as demand paging to allocate physical memory to active applications as needed while moving currently unused data to a pagefile on the hard drive. This process allowed the operating system to maintain a pool of free physical memory for more active applications while still being able to pull the data back from the pagefile and into memory if an application requested it. According to Microsoft, research has shown that demand paging generates many disk I/O requests, can create usage patterns resembling random I/O, and contributes to poor system performance due to the lack of optimal in-memory content and large latencies caused by disk seeks. Windows SuperFetch and related technologies in Windows Vista and Windows Server 2008 act to reduce these latencies by analyzing memory usage patterns to determine the optimal memory content for a given user and actively working to keep necessary content resident in memory rather than reflexively fetching it upon request. 

SuperFetch uses a lightweight, sophisticated tracking algorithm to determine which pages a user uses most frequently. As a user goes about her daily activities, SuperFetch builds a history of what information is most likely to be needed. To build an effective page list, SuperFetch tracks several aspects of the user’s computing session including but not limited to foreground application, time of day, day of the week, and even whether the user is currently using the PC. When the PC has free physical memory, SuperFetch places candidate pages into the physical memory cache so Windows Vista can move them directly into the working set instead of pulling them from disk. This provides data when the user needs it, makes the PC more responsive, and eliminates delays caused by random disk I/O. Flash memory devices can also be utilized to reduce or eliminate mechanical latencies and reduce contention during simultaneous I/O requests.

Windows ReadyBoost
Windows ReadyBoost works in concert with Windows SuperFetch to increase system I/O performance and reduce latencies. By using storage space on compliant removable media devices, such as some USB flash drives, SD and Compact Flash cards, Windows ReadyBoost can speed up your computer. When you insert a Windows ReadyBoost compliant device, the AutoPlay dialog will offer you the option to speed up your system using Windows ReadyBoost. If you select this option, you can then choose how much memory to use for this purpose. There are some situations where you may not be able to use all of the memory on your storage device to speed up your computer. Some USB flash drives contain both slow and fast flash memory, and Windows can only use the fast flash memory to speed up your computer.

 

Windows ReadyBoost cache sizes can range from 230 MB up to 4 GB. Microsoft recommends at least a 1:1 ratio of ReadyBoost cache size to main memory (RAM) capacity. Higher ratios up to 3:1 will realize optimal performance benefits. For instance, if your computer has 512 MB of RAM and you plug in a 4 GB USB flash drive, setting aside from 512MB to 1.5GB of that drive will offer the best performance boost. Every page of data in the ReadyBoost cache is a copy of a page on disk. If the device is removed from the computer, no data is lost, but the computer loses the performance boost and the operating system reverts to sending requests to the disk. All data written to the cache on the ReadyBoost device is compressed at a 2:1 ratio and encrypted using AES-128 to ensure security of user data.

Windows ReadyDrive
Like Windows ReadyBoost, Windows ReadyDrive reduces or eliminates mechanical latencies through the use of flash memory. ReadyDrive utilizes the flash memory in solid state and hybrid harddrives to act as additional capacity for SuperFetch, act as a write buffer for traditional hard drives, and provide a persistent storage area for OEMs, ISVs, and administrators to pin data to speed application loading upon system startup and resume, such as for launching Windows HotStart applications, or for accessing applications and data while the main operating system is offline, as with Windows Sideshow gadgets. 

　

　

Resources:

Symbolic Links
http://msdn2.microsoft.com/en-us/library/aa365680.aspx

Common Log File System (CLFS)
http://msdn2.microsoft.com/en-us/library/aa363836.aspx

Kernel Transaction Manager
http://msdn2.microsoft.com/en-us/library/aa366295.aspx

Selected Scenarios for Maintaining Data Integrity with Windows Vista
http://technet2.microsoft.com/WindowsVista/en/library/4ac505e6-dd8b-4ae7-80fa-b9d77cd8104d1033.mspx

Introduction to Storage Technologies
http://www.microsoft.com/whdc/device/storage/stor-tech.mspx

Windows PC Accelerators: Performance Technology for Windows Vista
http://www.microsoft.com/whdc/system/sysperf/accelerator.mspx