Windows NT Filesystems
FAT Filesystem Characteristics
Used with DOS, it can only support partitions up to 4 G. No spaces are allowed in the file name.
FAT32 or VFAT Filesystem Characteristics
VFAT - Virtual File Allocation Table introduced by Windows 95. Some documentation says NTWS cannot use FAT32.
- Filenames up to 255 characters long.
- Names begin with a letter and exclude " / \ [ ] : ; | = , ^ * ?
- The last part is the extension but spaces can be used
- It supports file attributes used by DOS such as read-only, archive, system, and hidden.
- Won't support running POSIX applications.
RISC computers can only boot from FAT filesystems. FAT filesystems support dual booting of operating systems. FAT partitions provide no local security, only share level security.
NTFS Filesystem Characteristics
- Filenames up to 255 characters long
- File names preserve case but are not case sensitive.
- Exclude " / \ < > : | * ?
- Supports built in file compression as a file attribute. Compression is applied to files in a folder if that folder has its compression attribute set. Also optionally sub folders and their contents may be compressed. Compression is not supported if the cluster size is above 4K in size. Moved files retain their compression attribute, but if they are copied they will assume the compression attribute of the target folder.
- Provides automatic transaction tracking of disk activity for correcting corrupt or failed operations.
- Supports auditing.
- Provides sector sparing
- There is a recycle bin for each user
- Windows 16 bit and DOS environments can't use this filesystem.
- A master file table is used to save individual file, boot sector, disk structure, and file recovery information.
- Automatically makes 11 character DOS file names. When the first 8 characters of long filenames match, the first four DOS file names use the first for characters of the long name, the ~ and 1, then2, etc. After the fourth duplicate name, the first two characters are used, then the next four characters are hashed, then the ~ character then a number. The first two duplicate file names may be: DOCU~1.DOC and DOCU~2.DOC. The long extension is used as part of the extension for the 8.3 filename alias.Directory entries used by long filenames include 1 for the 8.3 alias and 1 for each 13 characters in the long filename.
- Provides file logging ability and file recovery.
- Supports POSIX.
- Maximum file or partition size of 16 exabytes.
- Supports file sharing with MacIntosh clients.
- The disk is in 8M bands with a 2K file allocation map between each band. The 2K map is a map for the associated 8M band. This structure is called the BTREE and is used to reduce fragmentation.
On RISC computers a FAT filesystem of at least 2Mb must exist to boot from and an NTFS volume can exist to install NT on. If installing DOS with NT, install DOS first so DOS will not corrupt the NT boot sector and stop the NT boot manager from running. Floppies are formatted as FAT, not NTFS.
A hard drive may be split into partitions. NT uses two main partitions but I believe these two may be installed on one partition. There can be up to 4 primary partitions and only one extended partition which may include several logical drives. Only one partition may be active at a time. On IBM compatible computers, only a primary partition may be a system partition which is where the NT boot loader must reside.
- System - Stores system files for booting such as NTLDR, BOOT.INI, and NTDETECT.COM.
- Boot - WINNT_Root partition where system files are
The filesystem containing the boot files is referred to as the system partition and the partition that contains the WINNT40 directory is the boot partition.
A volume may span several partitions and includes:
- The disk directory area also called the root directory.
- Allocation tables to track used disk space.
Characteristics and limitations:
- A volume may contain 1 to 32 disk areas and can be formatted as FAT or NTFS.
- These combined areas cannot be split or one part of a volume can't be deleted without destroying the entire volume.
- They may contain disk areas from various drive types such as IDE or SCSI.
- NT system and boot partitions cannot be part of a volume set. Windows 95 and DOS don't recognize volume sets.
A stripe set is established using free space from between 2 and 32 physical hard drives. The free space on each drive must be the same capacity. Data is written is 64k blocks simultaneously on each drive in the stripe set which increases disk drive read and write access speed. NTWS supports stripe sets, but not stripe sets with parity. NT workstation does not support disk drive fault tolerance, only supporting stripe sets without parity and sector sparing.
NT system and boot partitions cannot be part of a stripe set.
Other NT fault tolerant options include:
- RAID 5 or stripe sets with a parity drive
- Disk mirroring
- Sector hot fixing
Other NT file and filesystem characteristics that enhance file storage:
- Confirmation that hard drive write requests were done.
- Disk cache is used to store data going to or from the disk to speed up access time. This is referred to as lazy writing.
- Hard links are used to tie file physical location to multiple file names.