Operating System MCQs
1K+ questions with answers
The time taken for the desired sector to rotate to the disk head is called ____________
When the head damages the magnetic surface, it is known as _________
What is the host controller?
______ controller sends the command placed into it, via messages to the _____ controller.
What is the disk bandwidth?
Whenever a process needs I/O to or from a disk it issues a ______________
If a process needs I/O to or from a disk, and if the drive or controller is busy then ____________
Consider a disk queue with requests for I/O to blocks on cylinders. 98 183 37 122 14 124 65 67 Considering FCFS (first cum first served) scheduling, the total number of head movements is, if the disk head is initially at 53 is?
Consider a disk queue with requests for I/O to blocks on cylinders. 98 183 37 122 14 124 65 67 Considering SSTF (shortest seek time first) scheduling, the total number of head movements is, if the disk head is initially at 53 is?
Random access in magnetic tapes is _________ compared to magnetic disks.
Magnetic tape drives can write data at a speed ________ disk drives.
SSTF algorithm, like SJF __________ of some requests.
In the ______ algorithm, the disk arm starts at one end of the disk and moves toward the other end, servicing requests till the other end of the disk. At the other end, the direction is reversed and servicing continues.
In the _______ algorithm, the disk head moves from one end to the other, servicing requests along the way. When the head reaches the other end, it immediately returns to the beginning of the disk without servicing any requests on the return trip.
In the ______ algorithm, the disk arm goes as far as the final request in each direction, then reverses direction immediately without going to the end of the disk.
The process of dividing a disk into sectors that the disk controller can read and write, before a disk can store data is known as ____________
The data structure for a sector typically contains ____________
The header and trailer of a sector contain information used by the disk controller such as _________ and _________
The two steps the operating system takes to use a disk to hold its files are _______ and ________
The _______ program initializes all aspects of the system, from CPU registers to device controllers and the contents of main memory, and then starts the operating system.
For most computers, the bootstrap is stored in ________
Defective sectors on disks are often known as __________
In SCSI disks used in high end PCs, the controller maintains a list of _________ on the disk. The disk is initialized during ________ which sets aside spare sectors not visible to the operating system.
In SCSI disks used in high end PCs, the controller maintains a list of bad blocks on the disk. The disk is initialized during low-level formatting which sets aside spare sectors not visible to the operating system. The scheme used is known as _______ or ________
An unrecoverable error is known as _________
Virtual memory uses disk space as an extension of _________
Using swap space significantly _________ system performance.
Linux __________ the use of multiple swap spaces.
A single swap space ______ reside in two places.
If the swap space is simply a large file, within the file system, ____________ used to create it, name it and allocate its space.
For swap space created in a separate disk partition where no file system or directory structure is placed, _____________ used to allocate and deallocate the blocks.
In UNIX, two per process ________ are used by the kernel to track swap space use.
It is __________ to reread a page from the file system than to write it to swap space and then to reread it from there.
RAID level 3 supports a lower number of I/Os per second, because _______________
RAID level _____ is also known as block interleaved parity organisation and uses block level striping and keeps a parity block on a separate disk.
A performance problem with _________ is the expense of computing and writing parity.
In RAID level 4, one block read, accesses __________
The overall I/O rate in RAID level 4 is ____________
A write of a block has to access ____________
RAID level ____ spreads parity and data among all N+1 disks rather than storing data in N disks and parity in 1.
The potential overuse of a single parity disk is avoided in RAID level _______
RAID level 0+1 is used because, RAID level 0 provides ______ whereas RAID level 1 provides ________
If a disk fails in RAID level ___________ rebuilding lost data is easiest.
Where performance and reliability are both important, RAID level ____ is used.
A large number of disks in a system improves the rate at which data can be read or written if ____________
RAID stands for ____________
If the mean time to failure of a single disk is 100,000 hours, then the mean time to failure of some disk in an array of 100 disks will be ____________
The solution to the problem of reliability is the introduction of __________
The technique of duplicating every disk is known as ____________
The mean time to failure of a mirrored disk depends on ____________ I) the mean time to failure of individual disks II) the mean time to repair