Which variant of the SCAN disk scheduling algorithm reverses direction only when there are no more requests in the current direction, rather than traveling to the physical end of the disk?
Option D is correct. Option D is correct because both Option A (LOOK Algorithm) and Option B (Valid alternative formulation of look algorithm) are valid features/answers.
Which variant of the C-SCAN disk scheduling algorithm moves servicing requests in one direction and returns to the furthest request in the opposite direction without traveling all the way to the disk boundary?
Option A is correct. C-LOOK is an optimized C-SCAN algorithm. It sweeps in one direction until the last request, then jumps directly back to the lowest requested cylinder.
In I/O system architecture, what is a Spooling (Simultaneous Peripheral Operations On-Line) system primarily used for?
Option C is correct. Spooling intercepts output destined for non-shareable devices (e.g., printers) and writes it to disk first, allowing the device to process jobs sequentially without blocking applications.
Which memory area stores data temporarily while it is being transferred between two devices or between a device and an application to compensate for speed disparities?
Option A is correct. A Buffer is a temporary storage area in memory used to hold data during transfer, smoothing out speed differences between fast CPUs and slower I/O devices.
Which mechanism stores copies of frequently accessed disk data in fast main memory to speed up future read and write operations?
Option C is correct. Page Caching retains copies of disk blocks in RAM, allowing subsequent access to be satisfied at memory speed without physical disk reads.