How a Hard Disk Works
A hard disk looks like a small metal box no bigger than a man’s palm. Inside is a vertical stack of metal or glass platters which are mounted on a spindle motor. When the hard disk is switched on, the data-carrying platters begin to be spun rapidly by the spindle motor at a speed of 5,400 or 7,200 revolutions per minute (RPM), though there are some hard drives which spin at a staggering 15,000 RPM.
When the platters have picked up enough speed during the booting-up process, the actuator arm moves over them. The head stays afloat a sub-micron-level above the platters due to the air currents generated by the wildly spinning platters. The head then goes about doing its business of reading and writing data all over the platters following the commands of the operating system.
The platters are coated with a thin layer of magnetic paint which constitutes the actual data-recording surface. The data on the platters is written and accessed by a read / write head that is mounted at the end of a long actuator arm.
The head is actually an electromagnet that creates or modifies magnetic imprints on the platters. These imprints are then interpreted by the operating system as digital data. The platters have an under side and a top side. Both these sides carry data, with a separate head for each. Thus a hard disk that has four platters would be having eight different heads.
The vertical distance between the read / write head and the spinning platters is minuscule. When a dust particle or any other microscopic contaminant gets wedged between them, the head gets jammed and is unable to move. It scratches the data-recording surface as the platters continue to spin. This is called a head crash.
The head makes contact with the platters in a head crash and damages the data permanently by furrowing the recording surface. That is why it is advised to shut off the computer immediately the moment a head crash is suspected. A scratching sound coming from the hard disk is a strong indication that the head of the drive has failed or it is bouncing off the platters.
When a hard disk crashes, there is nothing much the user can do because the DIY recovery software is useless in this case. The only solution is to immediately contact a professional data recovery company for urgent repairs. The company engineers would take the disk to their clean room which has its air totally cleaned of all dust particles and other contaminants by powerful filters.
Hard disks have very high capacities. The commonly available ones are capable of storing up to 240 GB of data. Though having many sophisticated and precision parts inside, hard disks are designed to last for years altogether without giving any problem to the user.
Has YOUR Hard Disk Crashed?
A hard disk ‘crash’ is the expression of choice used by computer technicians and users to convey that the hard disk / hard drive of the concerned computer is either physically or logically affected, thereby not allowing for the reading or storing of data. The hard drive fails to work.
“I/O Error”, “Serious Disk Error Writing Drive C:”, are some of the ominous warning messages that your hard drive has finally decided to call it a day!
After powering on the computer, you cannot hear the low audible sound of the spinning hard disk (don’t confuse this with the sound of the SMPS fan) or the hard disk activity indicator on the front panel of the computer isn’t glowing. This could mean loose electrical or ribbon cable connections to the hard drive.
“Hard disk drive failure” or “Hard disk controller failure” flashing on your monitor screen could denote that the electronic Controller Board of your hard drive / hard disk (which orchestrates the hard drive’s operations) is faulty or has suffered an excessive surge of electric supply / electric spike. Power surges tend to destroy the logical structures of the hard drive, as well.
If the hard drive is forced to work in an environment full of air contaminants, excessive levels of humidity, high temperatures or salty air conditions, the metallic platters and the read/ write heads of the hard drive conjoin. So much so, the platters are unable to spin. This in turn damages the spindle motors and the hard drive just does not respond with any signs of physical activity. Air contaminants which swirl in and out of the hard drive, can get jammed between the accurate nano-spacing of the read/ write heads and the disk platters, thereby causing the read/ write heads to be in permanent physical contact with the platter and causing hard drive ‘crash’.
The drive spins but the system fails to recognise the drive. “No fixed disk present” or “Fatal Error - Cannot access hard disk“, is persistently displayed and the operating system software is unable to load. This type of error can be due to varying causes like improper jumper settings of the hard drive, loose hardware connections, bad CMOS settings or even due to damaged hard drive.
Mechanical failure of the hard drive is primarily caused due to development of faults / wear and tear of the components found internally within the hard drive. A regular ticking or a clicking sound is the audible indication of an impending hard disk failure.
Logical errors in the format of the hard drive frequently occur due to massive fragmentation of data, reformatting the hard drive, invalid entry in the file allocation table of the hard drive and improper re- partitioning of the hard drive. “Data Error Reading Drive C:” or “Error Reading Drive C:” or “Seek Error - Sector not found” are some common clues to logical errors in the hard drive.
Intentional destructive acts of viruses and other malware can also play havoc with the hard drive’s normal functioning.
All of these above causes and symptoms of the hard drive failure are not to be treated casually, if your data is precious.
Hard drives have a very short lifespan of 3-5 years, compared to the longevity of backup mediums like Tape drives, Thumb drives etc. Always factor in the reality that hard drives will sooner or later fail.
It is possible to slightly prolong the usefulness of your hard drive, if:
* A regular schedule of de-fragmenting the hard drive is undertaken.
* Scan Disk software is used to monitor the bad sectors of the hard drive.
* A constant eye is kept on the statistics logged by the S.M.A.R.T (Self-Monitoring, Analysis and Reporting Technology) facility, which is shipped with most motherboards and hard drives.
It is very much possible to be insured against the eventual failure, by taking regular backups of the hard drive data.
However, when the dreaded event happens and the hard drive is uncommunicative or erratic, rush it to the experts rather than trying to salvage it yourself. Sometimes, Do-it-Yourself software is able to help retrieve your data, but that's a big risk, when dealing with a hard drive whose extent of damage is unknown. Despite the presence of clean room facility, trained technicians and proper software, extricating data from the sunken hard drive is not an easy task even for the experts. Do not even dream of attempting any rescue operations, on your own.
