Storage Flashcards
1
Q
Disk Physical Structure
A
- Platters (the round part), tracks (circular sections of the platter), sectors (segments of the track), cylinders (same track across multiple platters)
- Read/write head moves horizontally from one track to another
2
Q
Disk Physical Structure
A
- Platters (the round part), tracks (circular sections of the platter), sectors (segments of the track), cylinders (same track across multiple platters)
- Read/write head moves horizontally from one track to another
3
Q
Disk is viewed and a ____ of logical blocks
A
One-dimensional array
4
Q
Each block is one…
A
…sector
5
Q
Array of blocks is mapped into…
A
…sequential sectors on the disk
6
Q
Block Address
A
7
Q
Disk Scheduling
A
- Processes issue kernel read/write requests
- Kernel maps these requests to logical block addresses
- These requests are sent to the disk controller
8
Q
Disk is viewed and a ____ of logical blocks
A
One-dimensional array
9
Q
Each block is one…
A
…sector
10
Q
Array of blocks is mapped into…
A
…sequential sectors on the disk
11
Q
Block Address
A
cylinder, track, sector
12
Q
Look
A
-Arm only goes as far as the last request in each direction
13
Q
Accessing a Block
A
- Move the head to the desired track (seek time)
- Wait for the desired sector to rotate under the head (rotational latency time)
- Transfer the block to a local buffer, then to main memory (transfer time)
- Try to minimize seek time, which is proportional to the distance moved by the head
14
Q
Disk Scheduling Algorithms
A
- First Come, First Served
- Shortest Seek Time First
- Scan/Circular Scan
- Look/Circular Look
15
Q
Shortest Seek Time First (SSTF)
A
- Select request with minimum seek time from current position
- May lead to starvation
