File Systems and Storage: Terms and Definitions, Quizzes of Computer Science

Download File Systems and Storage: Terms and Definitions and more Quizzes Computer Science in PDF only on Docsity! TERM 1 two characteristics that make disks convenient medium for storing multiple files DEFINITION 1 1. A disk can be rewritten in place; it is possible to read a block from the disk, modify the block, and write it back into the same place. 2. A disk cart access directly any given block of information it contains. Thus, it is simple to access any file either sequentially or randomly, and switching from one file to another requires only moving the read-write heads and waiting for the disk to rotate. TERM 2 what does and IO control consist of DEFINITION 2 device drivers and interrupt handlers TERM 3 file organization module DEFINITION 3 translates logical block addresses to physical block addresses for the basic file system to transfer. TERM 4 logical file system DEFINITION 4 manages metadata information. Metadata includes all of the file-system structure except the actual data (or contents of the files). TERM 5 file control block(FCB) DEFINITION 5 contains information about the file, including ownership, permissions, and location of the file contents. TERM 6 boot control block DEFINITION 6 contains information needed by the system to boot an operating system from that volume. In UPS, it is called the boot block; in NTFS, it is the partition boot sector. TERM 7 volume control block DEFINITION 7 contains volume (or partition details, such as the number of blocks in the partition, size of the blocks, block count and free-block pointers, and free FCB count and FCB pointers. In UFS, this is called a superblock; in NTFS, it is stored in the master file table. TERM 8 system-wide open-file table DEFINITION 8 contains a copy of the FCB of each open file, as well as other information. TERM 9 per-process open-file table DEFINITION 9 contains a pointer to the appropriate entry in the system- wide open-file table, as well as other infornlation. TERM 10 root partition DEFINITION 10 contains the operating-system kernel and sometimes other system files, is mounted at boot time. TERM 21 direct blocks DEFINITION 21 contain addresses of blocks that contain data of the file. TERM 22 single indirect block DEFINITION 22 an index block containing not data but the addresses of blocks that do contain data. TERM 23 double indirect block DEFINITION 23 contains the address of a block that contains the addresses of blocks that contain pointers to the actual data blocks. TERM 24 free-space list DEFINITION 24 records all free disk blocks-those not allocated to some file or directory. TERM 25 calculation of block number DEFINITION 25 (number of bits per word) x (number of O-value words) + offset of first 1 bit. TERM 26 buffer cache DEFINITION 26 blocks are kept under the assumption that they will be used again shortly TERM 27 page cache DEFINITION 27 uses virtual memory techniques to cache file data as pages rather than as file-system-oriented blocks. TERM 28 unified virtual memory DEFINITION 28 use page caching to cache both process pages and file data. TERM 29 double caching DEFINITION 29 Because the virtual memory system does not interface with the buffer cache, the contents of the file in the buffer cache must be copied into the page TERM 30 Synchronous writes DEFINITION 30 occur in the order in. which the disk subsystem receives them, and the writes are not buffered. TERM 31 Asynchronous writes DEFINITION 31 the data are stored in the cache, and control returns to the caller. TERM 32 free-behind DEFINITION 32 removes a page from the buffer as soon as the next page is requested. TERM 33 read-ahead DEFINITION 33 requested page and several subsequent pages are read and cached. TERM 34 consistency checker DEFINITION 34 a systems program such as fsck in UNiX or chkdsk in MS- DOS-compares the data in the directory structure with the data blocks on disk and tries to fix any inconsistencies it finds. TERM 35 circular buffer DEFINITION 35 writes to the end of its space and then continues at the beginning, overwriting older values as it goes.