Acronis diskeditor 6.0 User Manual
While MBR Partition table (of a physical disk) can address to 4 partitions at once,
the Extended Partition Record addresses to a chain of partitions that ends with a
partition, which the second record of EPR does not address.
the Extended Partition Record addresses to a chain of partitions that ends with a
partition, which the second record of EPR does not address.
Please note that the Extended Partition Record addresses not from the beginning of
a physical hard disk (MBR sector), but from the beginning of the Extended partition
(EPR sector).
The chain of extended records is continuous and non-branching. From the
angle of a physical disk, all logical disks are located in the area described in
the Partition table as the Extended partition.
angle of a physical disk, all logical disks are located in the area described in
the Partition table as the Extended partition.
Each logical disk from the Extended partition has the same structure as the
Primary disk partition: it begins with a bootsector (but the logical disk loader
is never used), and has the Partition table (Extended).
Primary disk partition: it begins with a bootsector (but the logical disk loader
is never used), and has the Partition table (Extended).
3.5
File Allocation Table (FAT) and Root Folder (Root)
The structure of a partition with the FAT file system was described above. A
partition begins with a bootsector containing a loader and a table describing
file system parameters.
partition begins with a bootsector containing a loader and a table describing
file system parameters.
Bootsector is followed by one or several File Allocation Tables (FAT), the
Root folder, and the Data area divided into clusters and used for storing
folders and files. (There may be a number of reserved sectors between a
bootsector and the first FAT copy.)
Root folder, and the Data area divided into clusters and used for storing
folders and files. (There may be a number of reserved sectors between a
bootsector and the first FAT copy.)
3.5.1
A File as a Chain of Clusters
A file on a disk is stored as a chain of clusters. A cluster consists of one or
more sectors, the number of sectors per cluster depends on partition size
and equals a degree of 2 (1, 2, 4, 8, 16, etc.). Each cluster has its number
with numeration beginning with 2.
more sectors, the number of sectors per cluster depends on partition size
and equals a degree of 2 (1, 2, 4, 8, 16, etc.). Each cluster has its number
with numeration beginning with 2.
The File Allocation Table (FAT) describes the order of folders and files in
clusters. Each cluster corresponds to a FAT element (a table cell).
clusters. Each cluster corresponds to a FAT element (a table cell).
FAT elements can indicate of the following values:
•
0 – free cluster,
•
2 – the number of the next element in a cluster chain (0FEFh – for
FAT12, 0FFEFh – for FAT16, 0FFFFFEFh – for FAT32),
FAT12, 0FFEFh – for FAT16, 0FFFFFEFh – for FAT32),
•
0FFF0h – 0FFF6h – reserved values,
•
0FFF7h – bad cluster,
•
FFF8h – FFFFh – last cluster in a chain.
26
Chapter 3 : Main Window View Modes