File Systems and Storage Management Practice Quiz (34 questions)

Explanation

A file is named, contains related information, and is recorded on secondary storage; its bits, bytes, lines, or records get their meaning from its creator and user. Treating the contents as unrelated or locating them in main memory changes the definition.

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The information in a file is defined by its creator, and its structure depends on its type. A shared structure for every file type or a structure determined by the device does not fit this principle.

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Typical attributes include a file's name, identifier, type, location, size, protection, and relevant time, date, and user identification. Contents and read, write, or seek operations are not attributes, while the listed attribute set also includes the identifier.

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Creating a file requires locating space in the file system and adding an entry for it in the directory. Releasing space and removing an entry are associated with deletion, while resetting length describes truncation.

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File reads and writes use system calls and a file-position pointer that advances after each operation; when a process uses one operation at a time, both can use a shared current-position pointer. Separate fixed pointers fail to track progress.

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Truncation releases a file's contents and resets its length to zero while preserving its attributes. Deletion instead removes the directory entry and releases the file's space.

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The operating system must support an executable-file structure to load and run programs, even when applications interpret other input files themselves. Spreadsheet, database, and archive structures are examples of other formats, not the required program-loading structure.

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Sequential access processes records in order, and each read-next operation advances the file pointer. Direct access selects a numbered block, while index access locates a block through pointers.

Explanation

Direct access treats a file as numbered fixed-length logical blocks that can be read or written in any order by specifying a block number. Sequential access advances through records in order, whereas index access follows a pointer found through an index.

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File protection controls requested operations, including listing and appending as well as reading, writing, executing, and deleting. User identity records are associated with access-control mechanisms, not the operations themselves.

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An access-control list associates a file or directory with user names and the types of access permitted to each user. The rwx scheme uses owner, group, and universe fields, while a password system relies on passwords rather than a user-and-permission list.

Explanation

The compact scheme divides users into owner, group, and universe and uses three permission fields that may encode read, write, and execute as rwx bits. An ACL instead associates named users with permitted access, and password schemes rely on passwords rather than these fields.

Explanation

The on-disk structures include two per-volume blocks, the file-system directory structure, and an FCB for each file. Mount tables and open-file tables are in-memory structures; the other alternatives misassign or omit the per-file FCB.

Explanation

When an unopened file is found, its FCB is copied into the system-wide open-file table, and the process gets an entry pointing to that system-wide entry. Storing the FCB only per process reverses the roles of the tables, while copying the directory or omitting the process entry misstates the opening sequence.

Explanation

The in-memory structures comprise the mount table, directory cache, both levels of open-file tables, and buffers for blocks being read or written. Boot and volume control blocks are on-disk structures, and a directory structure is not the same as its in-memory cache.

Explanation

A linear-list directory holds names and pointers in a sequential list, so finding an entry requires a linear search. A hash table uses a filename-derived value, a sorted list can use binary search, and chained overflow handles hash collisions.

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A hash-table directory computes a value from the file name and uses it to return a pointer to the corresponding name in the linear list. A linear list searches sequentially, a sorted list supports binary search, and chained overflow addresses collisions.

Explanation

Contiguous allocation stores a file in consecutive disk blocks and records the starting block and allocated length in its directory entry. Linked allocation uses pointers between potentially scattered blocks; indexed and clustered allocation describe different arrangements.

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Contiguous allocation supports both sequential and direct access, and its consecutive blocks usually require few disk seeks. Linked allocation is efficient for sequential access but requires following pointers to locate a particular block.

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Repeated allocation and deletion can divide free disk space into small holes, causing external fragmentation even when first-fit or best-fit is used. Internal fragmentation is unused space within allocated storage, while pointer overhead is space used to store links.

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Linked allocation represents a file as potentially scattered blocks connected by pointers, with the directory pointing to the first and last blocks. Contiguous allocation stores blocks consecutively, while indexed allocation uses an index structure.

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Linked allocation can add available free blocks to a file as it grows, avoids external fragmentation, and does not require compaction. Contiguous allocation can be constrained by the need for a sufficiently large consecutive free region.

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Linked allocation supports sequential access efficiently because the reader follows each block's pointer to the next. Direct access to a particular block is inefficient because pointers must be followed from the beginning.

Explanation

The directory stores the address of the file’s index block, which holds addresses of its data blocks. The first-data-block choice confuses the index address with a data address; the directory-entry choice reverses where the pointers are stored; the last-data-block choice describes linked allocation.

Explanation

The ith index-block entry points to the ith file block, so the seventh entry directly identifies the requested block without sequential traversal. Using the sixth entry is an off-by-one error; traversing data blocks confuses indexed with linked access; reading the entry as data confuses an address with the block contents.

Explanation

A cylinder is the set of tracks at one arm position, while each platter surface is organized into tracks and sectors. Calling the group a sector confuses a subdivision with the aligned tracks; calling it a track confuses one circular path with the set of tracks; the block-group choice does not describe this physical layout.

Explanation

Seek time is the arm’s movement to the desired cylinder; rotational latency is the wait for the desired sector to rotate under the head. Reversing the terms swaps the two mechanisms, transfer rate measures data flow rather than arm movement, and positioning time is the combined delay rather than one of its two parts.

Explanation

An SSD is nonvolatile memory used like a hard drive, and its lack of moving parts, seek time, and rotational latency can make it faster, more reliable, and lower-power than a magnetic disk. The spinning-platter and moving-head choices describe mechanical storage, while loss of data without power contradicts nonvolatility.

Explanation

Disk scheduling selects the next pending I/O request when the drive or controller is busy. Choosing a drive, encoding data, or granting process access describes a different decision.

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SSTF repeatedly services the pending request nearest the current head position, producing a total movement of 236 cylinders for this queue. The 640-cylinder total is the FCFS result; 183 is the farthest request's cylinder, not total movement.

Explanation

SCAN travels across the disk servicing requests, reverses at the end, and services requests in both directions; it is also called the elevator algorithm. C-SCAN does not service requests on its return trip, while SSTF and FCFS use different selection rules.

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C-SCAN services requests in one direction and makes its return to the beginning without servicing requests; SCAN services in both directions. SSTF chooses the nearest request, whereas FCFS follows arrival order.

Explanation

Low-level formatting divides a blank magnetic disk into sectors and writes each sector's header, data area, and trailer. Partitioning creates groups of cylinders, logical formatting creates file-system structures, and ECC checking detects possible corruption during I/O.

Explanation

Preparing a disk for file storage requires first partitioning it into one or more groups of cylinders and then logically formatting it by writing initial file-system structures. Low-level formatting creates sector structures, while ECC handling supports data-integrity checks during I/O.