A computer system designed to continue operating, without loss of or damage to programs and data, when part of the system breaks down or seriously malfunctions.
A computer system designed to fail gracefully, over a period of time, when an element of hardware or software malfunctions. A fail-soft system terminates nonessential functions and remains operating at a diminished capacity until the problem has been corrected.
A file that is the last previously valid set of a changing set of data. The father file is immediately preceded by a grandfather file and immediately succeeded by its son. The pairs of terms father and son, parent and child (or descendant), and independent and dependent are synonymous.
The process of reading an instruction or an item of data from memory and writing it in a register. Fetch is part of the execution cycle of a microprocessor; first an instruction or item of data must be fetched from memory and loaded into a register, after which it can be executed (if it is an instruction) or acted upon (if it is data).
File Allocation Table (FAT)
FAT is a table in a hard disk drive that maintained by the operating systems. It records where your physical your files are being placed, that is which clusters.
File Control Block
Abbreviated FCB. A small block of memory temporarily assigned by a computer’s operating system to hold information about a file that has been opened for use. A file control block typically contains such information as the file’s identification, its location on disk, and a pointer that marks the user’s current (or last) position in the file.
A condition in which files are broken apart on disk into small, physically separated segments. The condition is a natural consequence of enlarging files and saving them on a crowded disk that no longer contains contiguous blocks of free large space large enough to hold them. File fragmentation is not an integrity problem, although it can eventually slow down read and write access times if the disk is very full and storage is badly fragmented. Software products are available for redistributing (optimizing) file storage. In a database, a situation in which records are not stored in their optimal access sequence due to accumulated additions and deletions of records. Most database systems offer or contain utility programs that resequence records to improve efficiency of access and to aggregate free space occupied by deleted records.
The process of reconstructing lost or unreadable files on disk. Files are lost when they are inadvertently deleted, when on-disk information about their storage is damaged, or when the disk is damaged. File recovery involves the use of specialized utility programs, which attempt to rebuild on-disk information about the storage locations of information belonging to deleted files. Because deletion makes the file’s disk space available but does not remove the data, data that has not yet been overwritten can be recovered. In the case of damaged files or disks, recovery programs read whatever raw data they can find and save the data to a new disk or file in ASC|| or numeric (binary or hexadecimal) form. Files salvaged in this way might require editing to become usable. In some instances, however, such reconstructed files contain so much extraneous or mixed information that they are unreadable. The best way to recover a file is to restore it from a backup copy.
A file-storage device on a local area network that is accessible to all users on the network. Unlike a disk server, which appears to the user as a remote disk drive, a file server is a sophisticated device that not only stores files but manages them and maintains order as network users request files and make changes to them. To deal with the tasks of handling multiple – sometimes simultaneous – requests for files, a file server contains a processor and controlling software as well as a disk drive for storage. On local are networks; a file server is often a computer with a large hard disk that is dedicated only to the task of managing shared files.
A set of program or software embedded in a device that instructs how the device should execute or perform. Firmware may or may not be updated depending on the ROM chip type and design.
Any nonremovable storage, such as a large disk that is sealed permanently in its drive.
A file consisting of records of a single record type, in which there is no embedded structure information governing relationships between records.
A type of floppy disk, such as that used in the Apple 2, that uses both sides for storage that must be physically removed from the drive and “flipped” over because the drive can read only one side at a time. The user can turn a double-sided disk into a flippy-floppy by cutting an extra white-protect notch on the side opposite the original one. This practice is not generally approved of by disk and disk drive manufacturers, however, because the felt pad that rides on the disk surface opposite the single read/write head can damage data on that side of the disk.
A process that builds the file system to be used by the operating system.
is the first step in making the drive ready for use by a computer, it is a process that organises or allocates physical spaces for data storage. Usually a raw disk requires to go through 2 levels of formatting: low-level formatting and high-level formatting.
The drive is being physically divided into tracks and sectors. Nowadays, drives are usually sold with low level formatting already done by the disk manufacturer.
High-level formatting prepares drive partitions for the operating system by creating a root directory, from which all other subdirectories could be created, and creating a File Allocation Table (FAT), which keeps track of all information on the disks and all the relationships between different pieces of information.
Abbreviation for frequency-shift keying, a simple form of modulation in which the digital values 0 and 1 are represented by two different frequencies; used by early modems, such as those running at 300 bits per second.
Abbreviation for File-Transfer Access and Management, a communications standard for transferring files between different makes and models of computer.
Full Stroke Seek Time
see seek time