Microsoft KB Archive/129038

= Summary of Windows NT NTFS and FTDisk Data Recovery =

Article ID: 129038

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Workstation 3.5
 * Microsoft Windows NT Server 3.5

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This article was previously published under Q129038



SUMMARY
FtDisk, the Windows NT fault tolerant driver, provides the mechanisms for redundant data storage, volume management, and dynamic data recovery.



MORE INFORMATION
Dynamic data recovery is only available on SCSI drives. FtDisk works between the physical disk drivers and the file system drivers, and works with all the supported files systems (FAT, HPFS, and NTFS). Windows NT file system (NTFS) is the only file system with built-in data recovery mechanisms.

The table below lists the data recovery options available when you have FtDisk installed on an NTFS drive.

         SCSI Drive with       Non-SCSI drive or      Any type of          spare sectors         no spare sectors       disk drive

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Fault    1. FtDisk can        1. FtDisk can         N/A Tolerant    recover data          recover data Volume   2. FtDisk uses       2. FtDisk sends data sector sparing       and a bad-sector (replaces sector)    error to the file system 3. File system is    3. NTFS performs unaware of           cluster remapping the error

Non-Fault 1. FtDisk cannot     1. FtDisk cannot      1. Disk driver Tolerant    recover data          recover data           returns bad Volume                                                   sector error to file system

2. FtDisk sends      2. FtDisk sends       2. NTFS performs bad-sector error     bad-sector error       cluster remapping to file system       to file system 3. NTFS performs     3. NTFS performs cluster remapping    cluster remapping DATA IS LOST         DATA IS LOST        DATA IS LOST ---

Fault tolerant volumes include mirror sets (RAID 1) and stripe sets with parity (RAID 5).

Note: If FtDisk finds a bad sector on a fault tolerant volume, and the physical disk supports spare sectors, and has spare sectors available, FtDisk replaces the sector. This is true for all tree supported file systems (FAT, HPFS, and NTFS); the file system remains unaware of this mechanism.

For more information on NTFS, see "Inside the Windows NT File System" by Helen Custer.

Additional query words: prodnt ft ntfaqset

Keywords: KB129038

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