What is the purpose of a disk scheduler group of answer...

Name: what is the purpose of a disk scheduler group of answer choices to allocate disk space to files to manage the file systems buffer cache to optimize the order of disk io requests to perform e 31435
Uploaded: 2023-10-16T04:18:37-08:00
Duration: 4 min 30 s
Channel: Madhur L
Description: what is the purpose of a disk scheduler group of answer choices to allocate disk space to files to manage the file systems buffer cache to optimize the order of disk io requests to perform e 31435

What is the purpose of a disk scheduler? Group of answer choices To allocate disk space to files. To manage the file system's buffer cache. To optimize the order of disk I/O requests. To perform error correction on disk data.

Transcript

00:01 Hello student here the first question is why is rotational latency usually not considered in the disk scheduling? how would you modify sst, f scan and c scan to include the latency optimization? so this is the question.

00:16 So here rotational latency is usually not considered in the disk scheduling because it is difficult to predict the various dependency on the location of the data on the disk.

00:28 So however if latency optimization is desired sstf shortest job first, shortest time first, shortest scan time first, c scans and scan can be modified to take into account the expected rotational latency.

00:45 One way to modify sstf to include the latency optimization is to first give the importance request that are closer to the current rotational position of the disk head.

00:56 This can be done by calculating the expected rotational latency for each request and then scheduling the request with the lowest expected rotational latency.

01:07 Another way to modify sstf to include latency optimization to use a look ahead algorithm.

01:14 A look ahead algorithm examine the next few requests in the queue and schedule the request that will optimize the overall rotational latency.

01:23 C scan and scan can be modified to include latency optimization in a similar way.

01:31 The main difference is that c scan and scan moves the disk head in a specific direction so the expected rotational latency can be calculated more accurately.

01:41 Here are some specific examples of how to modify sstf to include the latency optimization.

01:47 Calculate the expected rotational latency for each request in the queue.

01:52 Sort the request in the queue in the ascending order of the expected rotational latency.

01:57 Schedule the request at the front of the queue.

02:00 Repeat step 2 to 3 until the queue is empty.

02:03 So this algorithm will schedule the request in a way that minimizes the overall rotational latency.

02:09 So it is important to note that optimizing for the rotational latency can lead to a longer seek time.

02:14 This is because the disk head may have to move to a different cylinders in order to schedule the request with the lowest expected latency...

Question

What is the purpose of a disk scheduler? Group of answer choices To allocate disk space to files. To manage the file system's buffer cache. To optimize the order of disk I/O requests. To perform error correction on disk data.

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