Acronis os selector 8.0 User Manual
For more detailed information about file systems see paragraph 2.3 «File Systems».
Formatting of a whole hard disk for one file system heavily limits the number of
operating systems that can be installed on this hard disk. Fortunately this problem
can be solved. Prior to logical formatting a hard disk it must be
can be solved. Prior to logical formatting a hard disk it must be
partitioned
. Each
partition can then be formatted with its own file system. This will allow installing
different OSes. Partitioning also allows more efficient use of disk space.
For more detailed information about partitions see paragraph 2.4 «Partitions».
2.3 File
Systems
All file systems consist of structures that are necessary for data storage and
management. These structures usually include the operating system boot
record, folders and files. File systems perform the following basic actions:
management. These structures usually include the operating system boot
record, folders and files. File systems perform the following basic actions:
1. Allocated and free space (and bad sector) tracking.
2. File names and folders support.
3. Tracking of physical file positions on the disk.
2. File names and folders support.
3. Tracking of physical file positions on the disk.
Different file systems are used by different operating systems. Some
operating systems can use only one file system, while others are able to use
multiple ones. Let us now go into more details about some of the most
widely used file systems.
operating systems can use only one file system, while others are able to use
multiple ones. Let us now go into more details about some of the most
widely used file systems.
2.3.1 FAT16
FAT16 file system is used widely in DOS-compatible operating systems (DR-
DOS, MS-DOS, PC-DOS etc.), Windows 95/98/ME, Windows NT/2000/XP, and
is supported by most of the other operating systems.
DOS, MS-DOS, PC-DOS etc.), Windows 95/98/ME, Windows NT/2000/XP, and
is supported by most of the other operating systems.
Main FAT16 features are the file allocation table (FAT) and clusters. FAT is
the core of the file system. For better security several copies of FAT exist
(usually 2). A cluster is the minimum data storage unit in the FAT16 file
system. One cluster contains a fixed number of sectors that equals to a
power of 2. FAT stores the information about which clusters are free,
allocated or bad, and also tells which files are stored in which clusters.
the core of the file system. For better security several copies of FAT exist
(usually 2). A cluster is the minimum data storage unit in the FAT16 file
system. One cluster contains a fixed number of sectors that equals to a
power of 2. FAT stores the information about which clusters are free,
allocated or bad, and also tells which files are stored in which clusters.
Maximum FAT16 file system size is 4 GB, maximum number of clusters is
65525 and maximum cluster size is 128 sectors. Usually the minimum cluster
size that results in not more than 65525 clusters is chosen. The more the
partition size the more the cluster size has to be. Many operating systems
work with 128-sector clusters incorrectly, thus reducing the maximum size of
a FAT16 partition to 2 GB.
65525 and maximum cluster size is 128 sectors. Usually the minimum cluster
size that results in not more than 65525 clusters is chosen. The more the
partition size the more the cluster size has to be. Many operating systems
work with 128-sector clusters incorrectly, thus reducing the maximum size of
a FAT16 partition to 2 GB.
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