[Internet of Things] Magnetic media storage device—mechanical hard drive

A magnetic media storage device is a device that uses magnetic materials as storage media for storing and reading data. Common magnetic media storage devices include hard disk drives (HDDs), floppy disk drives, and tapes.

1. Basic structure and classification of mechanical hard disk memory

A mechanical hard disk drive (HDD) is a storage device that uses rotating platters and moving heads. Its basic structure includes platters, heads, tracks, and sectors . The basic structure and classification of mechanical hard disk memory will be described in detail below.

1.1 Basic structure

1. Platter : Mechanical hard drives are usually composed of multiple platters. Each platter is a circular thin slice made of materials such as aluminum or glass. The surface of the platter is coated with magnetic material and is used to store data. The platters are connected together by a spindle and rotated by a motor.

2. Head : Each platter has two heads, one on the top of the platter and one on the bottom. The magnetic head senses the magnetic field on the disk through a magnetic field sensor and converts it into an electrical signal. The heads are connected together by an arm mechanism that allows them to move over the platter.

3. Track : The surface of the disc is divided into many concentric circles, each track has a unique number. The heads can move across the tracks to read and write data. The density of the tracks determines the storage capacity and data density of the hard drive.

4. Sector : Each track is divided into many sectors, each sector can usually store 512 bytes or more of data. A sector is the smallest unit of data in hard disk memory. The magnetic head can be positioned on the track to specific sectors to read and write data.

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1.2 Classification

1. SATA hard drive : A SATA (Serial ATA) hard drive is a hard drive that is connected to a computer using a serial interface. It has high transmission speed and low cost and is widely used in personal computers and servers.

2. SAS hard disk : SAS (Serial Attached SCSI) hard disk is a hard disk connected to a computer using a serial interface. It has higher transmission speed and more reliable performance, and is suitable for high-performance servers and data centers.

3. IDE hard disk : IDE (Integrated Drive Electronics) hard disk is a hard disk connected to a computer using a parallel interface, which is a common type of hard disk in early computer systems.

4. SCSI hard disk : SCSI (Small Computer System Interface) hard disk is a high-performance hard disk connected to a computer using a parallel interface, suitable for high-performance applications such as servers and workstations.

5. External hard drive : An external hard drive is a hard drive that can be connected to a computer through USB, eSATA and other interfaces. It is portable and easy to use.

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2. Information distribution of hard disk

1. Platter Surface : A mechanical hard disk usually consists of multiple platters, each of which has two surfaces (also known as a recording surface). Data will be stored on these record surfaces.

2. Track : The surface of each disk is divided into multiple concentric circles. Tracks are the basic unit of data storage. Each track contains multiple sectors.

3. Cylinder : The same tracks (located at the same radius) on all platters in a mechanical hard disk form a cylindrical surface. A cylinder is a logical unit of data storage on a hard disk, and a computer system accesses data by specifying the number of the cylinder.

4. Sector : Each track is divided into multiple sectors. A sector is the smallest unit of data storage on the hard disk. Typically, each sector is 512 bytes or 4KB in size.

The way data is stored on a mechanical hard drive is by using magnetic heads to locate and access different tracks, cylinders, and sectors. The heads can read or write data based on designated tracks, cylinders, and sectors. In this way, mechanical hard drives can achieve random access and storage of data.

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3. Technical parameters of mechanical hard disk

1. Capacity : The capacity of a mechanical hard drive is usually measured in bytes, indicating the amount of data that the hard drive can store. Common mechanical hard drive capacities range from hundreds of GB to several TB.

2. Rotational Speed : The rotational speed of a mechanical hard disk refers to the speed at which the platter rotates, usually expressed in revolutions per minute (RPM). Common mechanical hard drive speeds are 5400 RPM, 7200 RPM or 10000 RPM. The higher the rotational speed, the faster the hard drive can read and write.

3. Cache : Mechanical hard drives usually have a cache (also called a buffer) of a certain size, which is used to temporarily store read or written data. The size of the cache is usually measured in MB, with common cache sizes being 8MB, 16MB, 32MB or 64MB.

4. Interface : The connection between the mechanical hard disk and the computer system is called the interface. Common interfaces include SATA (Serial ATA) and SAS (Serial Attached SCSI). The SATA interface is used in most personal computers and consumer hard drives, while the SAS interface is mainly used in servers and high-performance storage systems.

5. Average Seek Time : The average seek time refers to the average time required for the hard disk head to move from one track to another. It is usually expressed in milliseconds (ms). The shorter the average seek time, the faster the access speed of the hard disk.

6. Bad Sector Rate : Bad Sector Rate refers to the proportion of unusable or damaged sectors on the hard disk. The lower the bad sector rate, the higher the reliability and stability of the hard drive.

7. Data transfer rate : Data transfer rate refers to the speed at which data is read or written from a hard drive, usually measured in the amount of data transferred per second (such as MB/s).