Organization of the file system
In real blocks of data stored data files. Logical data block size can ask if the
file system formatting. Completing disc content information involves the use of
blocks of data storage for files and directories and files conventional
modification is the result of the array index nodes and data describing disk
space. Separately extracted data block may belong to one and only one file in
the file system. Realization directories As already mentioned, the directory or
folder is a file that has a certain type and keeps a list of its files or
directories. The main task faylov-direktory support for a hierarchical tree
structure of the file system. Writing in the directory has a certain format to
the OS, the user is often unknown, so blocks of data fayla-direktorii not filled
through the operation, and with the help of special system calls (such as file).
For access to the file path uses OS (pathname), reported by the user. Writing in
the directory connects a file name or the name poddirektorii with blocks of data
on the disk. Depending on the system, this link can be an entire disc address
file (continuous location), the first unit number (linked list), or index number
hub. In all cases, the primary function of the system directory-transform the
symbolic name of the file in the information needed to find the data. A separate
problem is a way to store file attributes. Sometimes they keep a direct entry in
the directory. For systems with the index nodes can be stored in the attributes
of the index node, but not in the records in the directory. As we will see later,
this method has several advantages in the organization shared access to files.
Consider a few specific examples. Examples of the implementation of certain
directories in OS Directories in OS CP / M In OS CP / M only one directory. Each
record contains the following-line fields: ID, owner, file name, file type,
extent box, which shows whether enough to identify a single file line, or even
the number of units, number of blocks. That is, the addresses of all file blocks
are listed in the entries in the directory! Directories in OS MS-DOS In OS MS-DOS
model entry in the directory is displayed: In MS-DOS OS, as in most modern OS,
the directory can contain poddirektorii (spetsifitsiruemye bit attribute), which
allows arbitrary construct a file system directory tree. Number of the first
block is used as an index in the table FAT. Next on the chain can be found the
remaining blocks.
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