Dane Elec Compact

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Hard Disc Drive Basics

Hard Disc Drive Basics
By: Muthu Senthil Kumar (mskumar@tataelxsi.co.in / mskumar86@myway.com)


This article describes the major technical foundation for hard drive and functioning. I focus on my attraction to the prospect particular to describe the physical and logical hard drive, Reading and Writing in the hard disk, How much data is stored on making and played some information on the hard disk interfaces. This article also highlights the smart technology company working on this hard drive and the units of this technology related.

From hard drive:

Hard Drive is the magnetic device used to store electronic copies of data as 0 and 1's. Specific drivers are used to recover the data back in a specified format. Magnetic hard disks are used from 1956. That day, hard disk size is too large for a small amount of storage and it also takes longer to store and retrieve. But today we are using very compact, high capacity, high latency disk drives to our systems.

the physical representation of your hard disk:

Data login / information are stored in a support surface of a disc. The media is a specially coated surface. Each surface is divided in the media communication tracks and sectors. These sectors are often called "blocks." The tracks are often referred to as cylinders. The track, the disk sector separations drive is shown below. The Cylinder, Head, Sector (CHS) provides a physical location.

logical representation of your hard disk:

Hard drives circular trays used to store data on hard. Each disc has two sides. Both sides of the media used to store information. If Each surface had 4 tracks and 4 indicates that some sectors would be 32 sectors or blocks. Each surface requires a "head" to read / write information. The surfaces are often referred to as the "head." A cylinder is the area that a boss can write or read from the outside is placed to another track.

Take a hard disk has two surfaces and the head, four sectors / blocks, then the logical representation of that record will be like Figure 3. In this figure, two heads of the disk represented as 0 and 1. The four cylinders / tracks and sectors are represented by 0 to 3. So for, each area has 16 logical sectors / blocks is termed as logical block addressing (LBA).

The Host and the file system using this LBA HDD only for the operation as read, write data, and search for etc. but for the leaders and the media, the drive circuitry to convert the hard disk LBA CHS (cylinder, Head, Sector).

Reading and writing to hard disk:

Hard disk drive is a data storage device that reads and writes digital data through changes of magnetization of a magnetic storage disk. This includes one or more media storage accessible random rotational or disks. In a magnetic disk drive, the data is encoded as bits of information using magnetic field investments grouped into tracks in the magnetic surface rotating hard disks. It also includes a transducer supported by a hydrodynamic bearing which flies above each magnetic disk. The transducer head supported by an actuator arm is used to read data or write data on disks. Hard drives are an indispensable component in modern computing systems management data.

Hard disk drives are commonly used to store relatively large amounts of data in computer systems today as desktop. If the disk capacity is more, the computer can store and access more data. In a computer, a hard disk drive is connected to the central processing unit (CPU) through the system bus. computer architectures has a motherboard that includes a central processing unit and the system bus to which various peripherals, including a hard disk drive are connected.

In a hard disk drive, data signals are read and written to a rotating disc by a head, which moves substantially with respect to the disc. The head assembly is easy to read and write information on a surface of a rotating magnetic disk. Interconnection assembly includes a plurality of transmission elements, such as cables or fingerprints, to transmit data to and from the whole head. The suspension mounting positions head assembly in a generally constant, distance from the moving surface of the rotating disk. When the power goes off to end the use a computer, a strain of driving a spindle motor also stops for the speed of the hard disk rotated by the spindle motor gradually decreases. At this point, the magnetic head in the state to fly above the hard drive down the air flow over the surface of the hard disk.

The servo control system in usually performs two distinct functions:
• Locate the control
• Follow the following

The search function includes control in a controlled way to move the actuator arm so that the transducer head moves from an initial position to a position in the destination track. Reading / writing head is usually the one hand or placed in a larger body that flies over the disk and is typically referred to as a slider. The regulator has a smaller area covered such as surface air support. The air bearing surface typically comprises one or more lanes that generally a positive air pressure

The machine sends the read command to the hard disk logic is transferred to physical hard drive to send the specified data block to read. At the time of writing in memory, the host sends the WRITE command to the HDD. After receiving recognition, data is sent over the bus to write to the specified block.

HDD Interface:

A shared boundary between two or more units, defined by specific attributes, such as the functional characteristics (Phases, states, protocol), common characteristics of physical interconnection (cable, plugs), and signal characteristics (polarity, range voltage, time). This is known as an interface. There are two main ways the hard disk interface with the host. Son,

ATA (Advanced Technology Attachment)

PATA (Advanced Technology Attachment in parallel)

SATA (Advanced Technology Attachment standard)
SCSI (Small Computer System Interface)

ATA is a common interface used in many personal computers before the advent of SATA (Serial Advanced Technology Attachment). The initial version is a Parallel ATA. So after the emergence of SATA, it is usually called as PATA (Parallel Advanced Technology Appendix). It is the cheapest of the interfaces used in the system at other times. PATA can support data transfer up to 133 MB / s. Today PATA SATA replace this at all areas. But the recent UDMA133 version is used in some subsystems depends on the customer's need.

Serial Advanced Technology Attachment commonly known as SATA. Is the hard disk interface very common in all personnel systems. A SATA port allows a device to connect to it. The main disadvantage this is not compatible with older systems, without the use of additional components

Abbreviated as Small Computer System Interface. SCSI is commonly used in servers, and more in industrial applications that uses the home. Storage component is the famous subsystem used in all medium and small standard computer interfaces. A mechanism called "Cable Sharing" is used here. It can support data transfer speeds up to 320 MB / s.

HDD – Company Information:

In business, companies are different units through its shaft revolution per minute (RPM) and 4200 rpm hard drives, 5,400 rpm hard drives, 7200 RPM hard drives, 10,000 RPM hard drives, 15,000 rpm hard drives. These are all major manufacturers and businesses have work with hard drives and Marketing.

Audavi, Dane-Elec Memory, Dataslide, DTS, Dynamic Network Factory, EDGE Tech, Technology Excelstor, EZQuest Fantom Drives, Training, Freecom Technologies, Fujitsu, Hitachi, Imation, I / Omagic, Iomega, LaCie, Maxell, Miltope, NEC, Olix Technologies, PNY Technologies, Prostor Systems, Quantum, Samsung Electronics, SDK, Seagate, Shining Technology, Sony, Soyo, Toshiba, Verbatim, Western Digital

Hard disk failure:

Hard disk crashes are one of the most frustrating experiences with a computer. The inability to read data from the hard drive can make a computer useless. Even if the operating system can run, the data may be inaccessible or damaged. The only way to recover from a failure is usually restore the data back security on a new album with all the software installed from scratch. If there is no backup, then the data is lost either or will cost a lot for services Recovery will recover.
Deficiencies in car

The most common failure for a hard drive is something called a primary system failure. Failure primary system is becoming the head of the unit manages to touch a plate. When this happens, the magnetic media will be taped off the plate over his head and make which both data and the unit inoperable head. There is no clear recovery of such a failure.

Another common failure is due to imperfections in the magnetic media. Each time a disk sector not properly maintain the magnetic alignment data will be inaccessible.

Mobile systems tend to be likely to break dishes. This was due to the fact that most hard drive are made of glass plates and was susceptible to shocks.


For consumers to get a good idea of the life of a hard drive, a drive was evaluated by MTBF. To mean time between failures and is used to represent the amount of time that 50 percent of the units fail before and 50 percent fail after. It is used to give an idea to a purchaser as to the amount average time that the device will work for. The "Mean Time Between Failures (MTBF) for hard disk drives has been rising fairly steadily from about 200,000 hours in 1990 to about 1,200,000 hours of today.

Recovery Software:

At the time of hard disk failure, the user wants to retrieve all data from that hard drive failure. Several companies offer software hard disk recovery data recovery. Some of them would be free too.

About the Author

Muthu Senthil Kumar M – Design Engineer, Tata Elxsi Limited, ITPB Road, Whitefield, Bangalore – 560048, India – Mail: mskumar@tataelxsi.co.in – Phone: +91 9916516728.