Hard Disk Drive_250621_103939

A sector is the basic unit of data storage for read/write operations in a Hard Disk Drive (HDD).

A cylinder is formed by the collection of tracks with the same number across different surfaces of the disks in a Hard Disk Drive (HDD).

In the example, each disk has 2048 tracks, and each track is divided into 40965 sectors.

The size of the HDD is 80 TB, calculated as follows:

1. Formula: 10×2 (双向)×2048×4096×512KB
2. Simplified: 20x2" x 2^12 x 2^19 Byte
3. Final Calculation: 20 x 2^42 bytes = 80 TB

The size of one cylinder is calculated as follows:

1. One cylinder consists of 20 tracks.
2. Size of one cylinder = 20 x 4096 x 512KB.

The three key components are seek time, rotational latency, and transfer time.

Seek time is the time it takes for the read/write head to move to the correct track on the disk where the data is located, impacting the overall speed of data retrieval.

Rotational latency is the delay waiting for the desired sector of the disk to rotate under the read/write head, affecting the time it takes to access data.

Transfer time is the duration it takes to transfer the data from the disk to memory once the head is in position and the sector is under the head.

The average rotational latency time can be calculated as follows:

1. RPM = 6000, which means 6000 revolutions per minute.
2. In one second, the number of revolutions is 6000 / 60 = 100.
3. Therefore, the time for one revolution is 1 / 100 seconds = 0.01 seconds.
4. The average rotational latency time is half of this, which is 0.01 / 2 = 0.005 seconds or 5 milliseconds.

To calculate the transfer rate:

1. Total data capacity = Number of sectors × Size of each sector = 2048 sectors × 512 KB/sector = 1,048,576 KB = 1024 MB.

2. The transfer rate can be determined by the time taken to read all sectors in one revolution. Since there are 100 revolutions per second (from the previous calculation), the transfer rate is:

   Transfer Rate = Total Data Capacity / Time per Revolution = 1024 MB / (1/100 seconds) = 102400 MB/s.

Thus, the transfer rate is 102400 MB/s.

The transfer rate can be calculated using the formula:

Transfer Rate = (Number of Tracks) × (Capacity per Track) × (Number of Cylinders) / (Time in seconds)

In this case, it is calculated as:

Transfer Rate = 100 × 20 × 2048 × 512 KB = 2000 GB/sec

The total time is calculated as follows:

• Seek time: 10 ms
• Rotation time: 1/200 seconds = 5 ms
• Transfer time: 2GB / 2000 GB/sec = 1 ms

Total time = 10 ms + 5 ms + 1 ms = 16 ms

A Hard Disk Drive (HDD) consists of multiple disks (double-sided) that store data. Each surface of the disk is made up of concentric circular tracks. Each track is divided into multiple sectors, which are the basic units for read/write operations by the disk controller. The collection of tracks with the same number on different surfaces is called a cylinder.