Thursday, August 8, 2013

Definition Hard Drive Computers and Components

Hard drive is a secondary storage device where data is stored as magnetic pulses on a rotating metal disc integrated. Data is stored in concentric circles called tracks. Each track is divided into several segments, known as sectors. To perform read and write operations of data to and from disk, hard disk using the head to do it, which is in every dish. Head is a moving hereinafter sector for sector-specific operations to be done to it. The time it takes to search for sectors called seek time. After finding the desired sector, then the head will rotate to look for tracks. The time it takes to search for this track is called latency.

Hard drive is a storage device that is designed to be used to save the data in a large capacity. It is against the background of the application programs are not allowed to be the first disk and also require large file storage media such as an agency database. Not only that, the hard drive is also expected to be offset from the speed of access.

Hard drive speed when compared with the usual floppy, very much. This is because hard drives have different mechanisms and materials technology, which is much better than the usual floppy. When no hard drive, you can imagine how much that must be provided to store employee data store of an agency or program applications. It is certainly not efficient. Plus the reading time is very slow when using the conventional disk storage media.

Definition Hard Drive Computers and Components

History of Hard Drive

Hard drive at the beginning of its development is dominated by giant companies that became standard computer that is IBM. Emerged in the years following the other companies such as Seagate, Quantum, Conner's up with Hewlett Packard in 1992. At first the technology used to read / write, the head read / wrote and metal plate to keep it in touch with each other. But at this time it is inevitable, because the rotational speed of the hard disk when high, touch the metal plate it will damage the physical storage of the disc.

But at this time it is inevitable, because the rotational speed of the hard disk when high, touch the metal plate it will damage the physical storage of the disc.

Figure 1: Evolution of Technology HDD According to IBM

From the figure it can be seen from 1984 to 2006 to come, the development of data storage technology is evolving rapidly. Ranging in size from micro to use the laptop to normal size for Desktop PC use.

Development Trend HardDisk

Harddisk development trend can be observed from the following characteristics:

a. Density Data / Materials Technology

A technological measure how much of the material used bits of data that can be stored in a unit square. In terms of density data from the beginning to present the evolution of highly contrasting. In the early development Gbits/in2 density is about 0004, but in 1999 IBM labs, there are about 35.3 Gbits/in2. But according be introduced what is called TerraBit density. Hard drive at the beginning of its development, the material used as a storage medium is iron oxide. But now widely used thin film media. This media is more media stores data from the iron oxide over the same area and also it is more durable.

b. Structure of the read / write head

Read / write head is the intermediary between the physical media to electronic data. Head through the data is written to or read from the physical medium physical medium. Head will turn bits of data into magnetic pulses and write to the physical medium. In the process of data reading process is the opposite.

Figure 2 Design characteristics most read / write head

The process of reading and writing of data is very important, therefore the mechanism is also noteworthy. Earlier in the introduction there are differences in the physical location of the head in its operation. Head first physical contact with the metal storage. Now between the head and the metal storage already given distance. When head contact with metal storage, it will cause permanent physical damage, head wear, of course the heat caused by friction. Especially now technology disk rotation speed is very fast. In addition, the hard drive head technology also evolved. Evolution of the read / write head disk: head Ferrite, Metal-In-Gap (MIG) heads, Thin Film (TF) Head, (Anisotropic) Magnetoresistive (MR / AMR) Heads, Giant Magnetoresistive (GMR) Heads and is now being used is Colossal Magnetoresistive (CMR) Heads. Ferrite head, is the head of the most ancient technologies, the core is made of iron U-shaped and wrapped by an electromagnetic coil. This technology is implemented in the mid-1980s at Seagate ST-251 hard drive. Most are on the hard drive size is less than 50MB. Metal-In-Gap (MIG), a refinement of Ferrite head. Typically used on hard drives the size of 50MB to 100MB. Thin Film (TF) heads, much different from the previous head types. Head is made with photolithography process as used in the manufacture of the processor. (Anisotropic) Magnetoresistive (MR / AMR) Heads, this head is used for reading only. Used for the writing head type Thin Film. Implemented on hard disk size 1GB up to 30GB. Giant Magnetoresistive (GMR) Heads, an invention of European researchers Peter Gruenberg and Albert Fert. Used in large sizes such as 75GB hard drive and a high density of about 10 to 15 Gbits/in2 Gbits/in2.

Due to technology Giant Magnetoresistive (GMR) began to be withdrawn from the market, as a successor is Colossal Magnetoresistive (CMR).

Play Speed ​​Disk

Rotational speed at the beginning of the era around 3600RPM. With the development of technology, the rotational speed was increased to 4500RPM and 5400RPM. Because the needs of storage media that has high capability was made with 7200RPM speed used on a SCSI disk.


Capacity hard drive at this point is reached the order of hundreds of GB. This is because the material is the better technology, higher data density. Technology from Western Digital is now able to make a 200GB hard drive with 7200RPM speed. While Maxtor with its Maxtor Maxline II is disk size of 300GB with 5400RPM speed. Along with the transition to a smaller hard drive size and capacity greater dramatic decline in the price per megabyte of storage, large capacity hard drive makes the price achieved by computer users.

Figure 3. System Control Head On each disc there is one head storage. To reach out to the middle side dish used sliders as the intermediary.

Hard drive technology in the Future

Hard drive in the future one of them put emphasis on access speed and capacity. This can be done by reducing the mechanical components of the physical hard drive. Mechanical components that are not able to work at high frequency is shifted to the electrical components that are capable of working in the order of MHz and even GHz.

Can be seen at this time already released various electronic storage media in the form of small. For example, USB Drive and MultiMedia Card. When will this technology can be applied and the price is affordable, computer capabilities of the access speed of read / write storage media will increase rapidly. Automatic PC Server capabilities to service the request from the client will increase.

Here's Some Quick Reference Summary About Hard Disk;

INTERFACE HARD DISK IDE (Integrated Drive Electronics);

Old standards that still exist. Cheap, and integrated with MB is the reason this technology theta p exist. Number of IDE there are 4 pieces per MB. Connection with flat cable 80 pin interface bottleneck and impede heat.

SCSI (Small Computer Standard Interface)

Speed ​​of 160 mb / sec SCSI type (SCASI I, Wide SCSI, Ultra wide) using a separate card. New technologies MB card is included SCSInya.

SCSI is typically used for server systems, which demand high performance SCSI system technology known as RAID, system preparation, writing, security with several HD.

RAID (Redundancy Array of Independent Disks), is a set diskdrive seen by the OS as a single drive. Recovery and security a priority.

Hard Drive Installation

IDE cables are red strip. Power supply plugged in adjacent or parallel to the red color on the IDE cable. If one computer will not boot. Perform detection of HD through BIOS.

HDD Read process

When an operating system sends data to the hard drive for recording, the drive process the data using a complex mathematical formula that adds an extra bit in the data. The bit does not take place: In the future, when the data is retrieved, extra bits allow the drive to detect and correct errors caused by random variation of the magnetic field inside the drive. Then, the drive head moves through the right tracks of the platter. Time to move the head is called "seek time". While on the right track, wait until the drive platter spins up to the desired sector is under the head. The amount of time is called "drive latency". The shorter the time `seek` `and` latency, the faster the drive completed its work. When electronic components drive determines that a head is in the right sector to write data, the drive sends electrical pulses to the head. Pulse produces a magnetic field that changes the magnetic surface on the platters. The recorded variations now represent a data. Reading data requires some recording process. Drive to position the reader part of the head above the right tracks, and then wait for the right sector to spin on it. When certain magnetic spectrum that represent your data in the right sectors and tracks just above the head reader, electronic components drive detect small changes in the magnetic field and turn it into bits. When finished checking the drive and corrects errors in bits if necessary, he then sends the data to the operating system.

Sectors and Tracks

Tracks is part of the circumference of the circle from the outside to the inside. While the sector is part of the tracks. Sectors have the number of bytes that have been set.

There are thousands sector in HD

1 512 byte sectors normally store information

Materials for Hard Disk

Currently hd made ​​with materials technology called thin film magnetic media. More meetings, its lifespan, small, light weight of oxide materials

Mechanism of Hard Disk

The process of reading and writing done by hd arm with magnetic Head Physical media, hard drives to convert bits to magnetic pulses and store it into the platters, and restore the data if the hard disk has done reading "Hard platter" which serves to keep the magnetic field. Basically how the hard disk is to use a magnetic field recording techniques. The workings of the magnet technique utilizing Iron oxide (FeO) or rust of iron, Ferric oxide (Fe2O3) or other oxide of iron. 2 oxide is a substance that is ferromagnetic, ie, if brought to the magnetic field it will be permanently withdrawn by the substance.


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