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ECE437 Module 6
Question | Answer |
---|---|
Which of the following disk head scheduling algorithms does not take into account the current position of the disk head? | FCFS (First Come First Serve) |
The SSTF scheduling algorithm | Services the request with the minimum seek time |
the surface of a magnetic disk platter is divided into | tracks |
DMA Controllers can... | steal memory access cycles from the main CPU |
On log-structured file systems, a transaction is considered only when it is written to disk. | False |
In general, LOOK disk head scheduling will involve less movement of the disk heads than SCAN disk head scheduling. | True |
LOOK disk head scheduling offers no practical benefit over SCAN disk head scheduling. | False |
Metadata includes all of the file-system structure, including the contents of the file. | False |
Which algorithm is considered reasonable for managing a buffer cache? | LRU (Least-Recently Used) |
Which of the following is true of the direct-access method? | It allows programs to read and write records in no particular order. |
The free-space list can be implemented using a bit vector approach. Which of the following is a drawback of this technique? | It is not feasible to keep the entire list in main memory for large disks |
The file-allocation table (FAT) used in MS-DOS is an example of | linked allocation |
A disk with free blocks 0,1,5,9,15 would be represented with what bit map? | 1100010001000001 |
What is used in UNIX systems at the beginning of some files to roughly indicate the type of the file. | magic number |
The simplest file access method is... | sequential access |
A mount point is... | the location within the file structure where the file system is to be attached. |
On UNIX systems, the data structure for maintaining information about a file is... | inode |
116, 22, 3, 11, 75, 185, 100, 87. Using the FCFS scheduling algorithm, what is the order that the requests are serviced, assuming the disk head is at cylinder 88 and moving upward through the cylinders? | 116 - 22 - 3 - 11 - 75 - 185 - 100 - 87 |
Indexed allocation may require substantial overhead for its index block. | True |
Linked allocation suffers from external fragmentation. | False |
RAID level 0 provides no redundancy. | True |
Which register of an I/O port can be written by the host to start a command or to change the mode of a device. | Control |
The path name "/home/people/os-student/chap10.txt" is an example of | an absolute path name |
Consider a system crash on a log-structured file system. Which one of the following events must occur? | All transactions in the log must be completed. |
Which of the following is the simplest method for implementing a directory? | linear list |
Which of the following allocation methods ensures that only one access is needed to get a disk block using direct access? | contiguous allocation |
In Unix/Linux environment where several processes may open the same file at the same time, the operating system typically uses... | two types of tables, called the system-wide and per-process tables, to keep track of open files |
Which of the following is true of the direct-access method? | It allows programs to read and write records in no particular order. |
Process A has 2 files open and process B has 3 files open. 2 files are shared between the two processes. How many entries are in the per-process table of process A, the per-process table of process B, and the system-wide open-file tables, respectively? | 2,3,3 |
Which of the following allocation methods ensures that only one access is needed to get a disk block using direct access? | contiguous allocation |
___ includes all of the file system structure, minus the actual data | Metadata |
___ I/O accesses a block device as a simple array of blocks. | Raw |
What are two components of positioning time? | seek time + rotational latency |
All files in a single-level directory must have unique names. | True |