Hard disk is one of the computers main storage medias.
It is composed by one or more of aluminum or glass platters.
The disk is covered with ferromagnetic materials.
The vast majority of the hard disks are permanently fixed in the hard disk drivers.
2.Mechanical hard disk(HDD, traditional hard disk) usually uses magnetic Disk to keep data.
It is the hard disk which integrates the magnetic disk and flash memory together.
Or using multiple magnetic heads on multiple disks to improve read and write speed.
Capacity
As a data memorizer in computer system, disks main parameter is capacity.
But in Windows operating system, it is still using the wordGB to represent theGiB.
Hard disk capacity indicator also includes single disk capacity.
The larger the single disk capacity is, the lower the unit cost is.
As a result, the average access time will be shorter.
It is the key factor to decide the internal transfer rate.
Whats more, it directly affects the speed of the hard disk.
Rotational speed of household hard disk is 5400 R/M or 7200 R/M.
Laptop users often use the disk with rotational speed of 4200 R/M or 5400 R/M.
Rotational speed in server requires higher performance than in household products.
High spindle speed can shorten the average seek time and the actual reading and writing time.
It embodies the hard disk read and write speed.
The average access time includes hard disk seek time and waiting time.
The Average Seek Time starts when the head moves and ends when the specified track is found.
The shorter the better.
Waiting time or latency is the time used for bringing the required sector under the read-write mechanism.
The average latency is one-half of the rotational period.
Data Transfer Rate (MB/s)
Data Transfer Rate means the hard disks read and write speed.
It can be divided into internal and external data transfer rate.
It mainly depends on the hard disk rotational speed.
It is associated withhard disk interfacetype and the caches size.
For Fast ATA interface, the biggest external hard drive transmission rate is 16.6 MB/s.
And as for Ultra ATA interface, the speed can reach to 33.3 MB/s.
In 2012, two young men developed a SSD with the transmission speed of 1.5 GB per second.
Cache Memory
Cache memory lies in the harddisk controller.
It is the buffer between hard disk internal storage and external interface.
Size and speed of cache can directly affect the hard disk transmission rate.
Cache can greatly improve the hard drive overall performance.
When hard disk gives access to data, constantly exchanging data between the disk and memory is a must.
Types of Interface
1.IDE (Integrated Drive Electronics)
It is commonly known as PATA parallel port.
The maximum speed of external interface is up to 133 MB/s.
Because of the poor anti-jamming and bad computer cooling, parallel line will be gradually replaced by SATA.
3.SATA (Serial ATA)
It adopts serial connection mode.
The Serial ATA bus uses embedded clock signal, and it has stronger ability of error correction.
Compared with the previous ones, it can check the transferring instruction and correct errors automatically.
SATA II
Unlike SATA, SATA IIs external transfer rate has been improved from 150 MB/s to 300 MB/s.
But not all of the SATA hard disks can support NCQ technology.
Not only the hard drive, but also the SATA controller of mainboard chipset should support NCQ.
SATA III (SATARevision3.0)
The transmission speed has been doubled to 6 Gbps.
It is compatible with SATARevision2.6 (or SATA3Gbps).
The interface and data line dont get changed.
SAS (Serial Attached SCSI)
It adopts the serial technology to gain higher transmission speed.
And it improves the internal space by shortening the link line.
This interface is designed to optimize the efficiency of storage system, availability and expandability.
And it also provides compatibility with SATA hard disk.
5.SCSI (Small Computer SystemInterface)
It is completely different from IDE ATA).
TheIDE Interfaceis ordinary PC standard Interface.
And SCSI is not specially designed for hard disk.
It features a high speed data transmission technology widely used in small machines.
Due to the high price, it is hard to get popularized.
Therefore, SCSI is mainly applied in medium or high-end servers and high grade workstations.
(Note:Seagate has launchedthe worlds thinnest 2TB mobile hard drivein 2016. )
Western Digital providing storage products for all five continents.
HITACH mainly produces desktop computer hard disks and notebook hard disks.
Then it was acquired by Western Digital.
TOSHIBA main productions are mobile storage devices.
Samsung its hard disks are used for desktop computers, mobile devices and electronics products.
In 2011, Seagate purchased Samsungs hard drive business.
It is developed to greatly improve the communication speed of multi-hard disk system.
Its main features are hot plug, high-speed bandwidth, remote connection, and support on large quantity equipments.
Fiber channel is designed for server hard disk system.
Traditional head is electromagnetic induction head which is a combination of reading and writing.
In addition, through the changes of resistance, the MR heads can induct the changes in signal amplitude.
It is quite sensitive to signal changes, and also can increase the data reading accuracy.
MR heads have been widely used.
There are concentric circles in the disk surface and information is stored in them.
Each circle equals to a track.
Sector:
A disk track can be divided into many arcs, and these arcs are calleddisk sector.
All the corresponding tracks taken together are called a cylinder.
A cylinder, composed by tracks, is a division of data in disk.
The amount of disk cylinders is the same as the amount of tracks.
It means that each track of the hard disk has the same number of sectors.
BIOS interrupt call 13hex:
It is used to transfer interrupt information in the process of inputting and outputting.
It also can support the removable media (such as active hard Disk).
Modern Structure:
In the old fashionable hard disk, each track shares with the number of sectors.
That is to say, the number of outer track sectors is larger than that of inner track.
After that, the hard drive no longer owns the 3D Disk Geometry.
And the addressing mode is also changed to linear addressing (or using sector for addressing).
1.Fast transmission rate
It can make many disk drives transmit data at the same time in some RAID mode.
And these disk drives are logically grouped in a disk drive.
Therefore, RAID can achieve a rate that is much faster than single disk drives.
Compared with ordinary disk drives, RAID mode provides a variety of data repair functions.
Maintenance Information About Hard Disk
Signs of Hard Disk Failure
S.M.A.R.T troubleshooting tips.
This is a built-in automatic detect program in hard disk.
It means that there are some physical faults in your hard disk.
Frequent but irregular crashes, especially while booting up Windows.
A number of errors orbad sectorsare scanned out.
And the checking procedure of Windows will report in detail.
Hard disk cannot be recognized in BIOS.
Or it can be found in BIOS butWindows cannot findit.
This is the most serious breakdown.
Maintenance Tips of Hard Disk
1.
And it can work in the indoor environment that doesnt have a purification equipment.
Using it in hot, cold, dusty or humid circumstances will make the disk suffer from damage.
Shut down the computer in right order
kindly pay attention to hard drive light in the panel.
Only when the light stops flicking, you’re able to turn down the computer.
Preventing the machine from being shut down improperly may make the hard disk get rid of destroy.
Dont move the hard disk when it is running.
When the disk runs at high speed, gentle shake may generate friction between head and disk platter.
In the process of mounting or dismounting, behaviors like violent shaking or collision should be avoided.
you could install two operation systems to avoid reading and writing on a sector for a long time.
Whats more, it shouldnt work continuously for 8 hours.
Therefore, the files cannot be kept to continuous sectors.
Making defragmentation at regular intervals is really a must.
Pleaseclick hereto know the benefits of defragmentation and how to defrag in Windows
7.
Provide stable power supply
Users should use the power with stable performance.
After a long time, the hard drive track will get damaged.
