Hard Drive Introduction

(i) The concept of hard disk and its composition

First of all, the concept of the hard disk: RTHK called the HDD, English name: Hard disk Drive, referred to as HDD, hard disk is one of the computer's main storage medium, consisting of one or more aluminum or glass-made discs. This is a hard drive: most of the hard drives are made up of a head arm bracket, a rotating shaft, a read-write head, a head arm, a track, a sector, a cylindrical surface, a disk surface.

(ii) SCSI hard drives:

Small computer System Interface (English: Small Computer system Interface; Abbreviation: SCSI), a stand-alone processor standard for system-level interfaces between computers and smart devices (hard disks, floppy drives, optical drives, printers, scanners, and so on). SCSI is an intelligent Universal interface standard.

Scsi-small Computer System Interface

SCSI It is a kind of high-speed data transmission technology which is widely used in small machine. SCSI interface has a wide range of applications, multitasking, large bandwidth, low CPU utilization, as well as hot Plug and so on, so the SCSI hard disk is mainly used in middle and high-end servers, high-end workstations and storage devices.

The SCSI interface is currently used with 68-pin and 80-pin interface specifications.

The SCSI interface is a parallel transport interface.

To emphasize, SCSI this kind of hard disk basically already eliminated, use very few similar to SATA replace Pata, SCSI also must be replaced by its upgrade product SAS (serial attached SCSI).

(iii) SAS hard drive:

The SAS English name is serial attached SCSI or serial attached SCSI. It is a serial interface.

The new generation of SCSI technology, and the current popular serial ATA (SATA) hard disk, are using serial technology to achieve higher transmission speed, and by shortening the link line to improve the internal space.

SAS is a new interface developed after the parallel SCSI interface. This interface is designed to improve the performance, availability, and extensibility of the storage system and to provide compatibility with SATA hard drives.

This better performance-the use of serial transmission instead of parallel transmission, Full-duplex mode, in fact, the serial technology is faster than the transmission speed of parallel technology.

Easier cabling-the flat, wide line of SCSI cables will no longer be used.

Wider scalability-compatible with SATA.

Lower costs-with the advantage of simplifying the internal connectivity design, you can reduce design costs by sharing components.

Look at this picture, this is the image of the SAS hard drive. This is the data cable interface, this is the power cable interface. It has two main sizes, one is 2.5 inches and one is 3.5 inches. SAS drives are typically used on servers.

This is a 1TB SAS hard drive for Seagate.

Its capacity is 1TB, the cache is 128M, rotate speed is: 7200 rpm.

Look at a hard drive that mainly looks at its speed, cache, and its capacity. This is the more important parameter of it.

(iv) The following is an introduction to the older hard disk: IDE hard disk.

The IDE, the integrated Drive Electronics, is meant to refer to a hard disk drive that integrates the controller with the disk, and the IDE is the transport interface that represents the hard disk. We often say that the IDE interface, also known as the ATA (Advanced Technology Attachment) interface, the PC is now used by the majority of the hard disk is IDE-compatible, just use a cable to connect them with the motherboard or interface card.

Look here, it is a parallel interface, relatively wide, this is the power cord, 4, the IDE is also a parallel transmission interface.

The IDE is no longer used, and now the most common on desktops are SATA drives.

(v) SATA hard drives

English is: Serial Advanced Technology attachment Serial ATA Interface specification.

• Also known as serial port IDE hard disk, is currently used in host and storage devices.

• 15-pin power plug, 7-pin data plug.

• Rates are 1.5gb/s and 3.0gb/s.

You can look at this picture, this is the SATA interface hard disk. 15-pin Power plug, 7-pin data plug.

Before the hard drive to IDE,SCSI, are the same port, now mainstream SAS, and SATA are serial ports. So why now with a lot of the use of the serial port of the hard disk.

(vi) The first is the speed ratio of the serial port of the block.

The serial port describes is a lane, and the mouth is 8 lanes. 8-bit (one-byte) data can be transmitted at the same time.

But not and tundish, due to the mutual interference between the 8-bit channels. The speed of transmission is limited. When the transmission goes wrong, the 8-bit data is retransmitted at the same time, and the faster the transmission, the more serious the interference. This is a mishap so that the speed cannot be lifted up.

There is no interference in the serial port, transmission error after the hair can be a. and the serial port transmission clock frequency is higher than and the mouth. That means my speed is faster than yours.

(vii) Solid-State drives:

A hard drive (Solid state drives), referred to as a solid disk (Solid state Drive), is made from a solid-state electronic memory chip array, consisting of a control unit and a memory unit (Flash chip, DRAM chip). We talked about the name of the mechanical hard drive, there is a disc has been turned, this is not, this solid-state drive consists of control unit and storage unit (flash chip, DRAM chip) two modules. And it is the same as your U disk, seismic performance is better, in the car and military, are not afraid of earthquakes.

Solid state hard disk in the interface of the specification and definition, function and use methods with the normal hard disk is identical to the product shape and size is also completely consistent with the common hard drive.

This is a Samsung 850 EVO series of an SSD parameter information.

2.5-inch, its interface, SATA 6GB/S, compatible with SATA 3gb/s, and normal desktop interface is the same, capacity is 250G, cache is 512M, read speed is 540MB, write speed 520MB per second, here is the capital B ah, SATA2 is about half as fast as SATA. Reference price is 589, SSD is also more expensive AH.

(eight) EFI

EFI, which is an extensible firmware interface, an abbreviation for the English name Extensible firmware Interface, is an upgrade program for a future class PC computer system that replaces the BIOS in an Intel-led PC technology development company. EFI's location is very special, unlike the BIOS that is the firmware and interface, EFI is only an interface between the operating system and the platform firmware. Why to say this, because some server bios is like this, not our old BIOS that kind of interface, is a character interface, and then is English. Now this is the graphical interface.

(ix) MBR and GPT partitioning tables:

MBR: Master boot records (Mbr,main boot record) are a section of boot (Loader) code that is at the front of the disk. That is, the existing hard disk partitioning mode. The standard for MBR partitioning determines that the MBR only supports hard drives under 2TB, and that more than 2TB of hard drives can only manage 2TB.

The

Gpt:guid disk partition table (GUID Partition table, abbreviated: GPT), which means "globally unique identity disk partition table", is the standard for the structural layout of partitioned tables for an entity hard disk. It is part of the Extensible Firmware Interface (EFI) standard, which is used by Intel to replace the PC's BIOS, and is used to replace a primary boot record (MBR) partition table that is 32bits in the BIOS system to store logical block addresses and size information. GPT has no restrictions on the number of partitions compared to the maximum of 4 partition table entries in the MBR. GPT can manage hard disk size up to 18EB, (1EB=1024PB=1048576TB)