Chat with AIExam 14: File-System Implementation
Describe UNIX inode concept.
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VerifiedFile’s inode is a data structure in a UNIX file system that describes a file or a directory. Each inode stores the attributes and disk block location(s) of the object's data by keeping, say, 15 pointers of the index block. The first 12 of these pointers point to direct blocks; that is, they contain addresses of blocks that contain data of the file. Thus, the data for small files (of no more than 12 blocks) do not need a separate index block. If the block size is 4 KB, then up to 48 KB of data can be accessed directly. The next three pointers point to indirect blocks. The first points to a single indirect block, which is an index block containing not data but the addresses of blocks that do contain data. The second points to a double indirect block, which contains the address of a block that contains the addresses of blocks that contain pointers to the actual data blocks. The last pointer contains the address of a triple indirect block.
The following characteristics of disks make them convenient for being the secondary storage:
(35) VerifiedC
When a boot control block may be empty?
(45) VerifiedIt could be empty if the disk does not contain an operating system.
What kind of in-memory information are used for file-system management?
(34) Why is the whole block not available to a user when linked allocation is used?
(37) Storage devices that do not allow overwrite (such as NVM devices) need only the free list for managing free space.
(30) What is the size of the bit vector of a 1TB disk with 512-byte blocks?
(31) Why should new allocation algorithms be developed for NVM (nonvolatile memory) devices?
(36) The file allocation table (FAT) has one entry for each block and is indexed by block number.
(29) The I/O control level consists of device drivers and interrupt handlers to transfer information between the main memory and the disk system
(36) In __________ write, the data are stored in the cache, and control returns to the caller.
(23) The consistency check is always able to recover the structures,
e.g., resulting in loss of files and entire directories.
(35) For counting method (used by free space management), the entries in the free-space list can be stored in a linked list, rather than a balanced tree, for efficient lookup, insertion, and deletion.
(33) The addresses of a given number of free blocks can be found faster using linked list rather than using grouping.
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