Hard Disk Fault Types?
In this article we will explore the four main types of hard disk failure: firmware corruption, electronic failure, mechanical failure and logical failure. These can occur either on their own or in combination. It is also worth noting that all hard disks have a life span and will eventually develop bad sectors at some stage.
1. Firmware corruption
Most people have heard of software (eg. computer programs) and hardware (eg. the hard drive) but not firmware. Firmware is actually software code that is embedded in the hardware and it serves to control the disk. This code can become corrupted such that the operating system (eg. Windows) can no longer communicate with the disk. As the stored data itself is usually unaffected, it is nearly always recoverable.
When a disk has a firmware error, it will usually spin up as normal but be recognised differently to how it usually is by the BIOS of the host computer. It is nearly always possible to successfully recover the data from the drive but to do so requires the drive's firmware to be reprogrammed by a data recovery company, who will then be able to recover the data.
2. Electronic failure
This refers to the printed circuit board, sometimes referred to as the hard drive's motherboard, which can be disabled by a sudden power spike or surge. It is sometimes possible to see burn damage around some of the chips on the hard drive's PCB. The hard disk doesn't spin when there is an electronic failure. There is usually no damage to the data stored on the drive so a full recovery is generally possible.
3. Mechanical failure
This type of failure refers to internal components of the disk becoming faulty. This type of problem usually presents as regular clicking or ticking sounds coming from the drive. It is important for a user not to take the cover off the drive; doing so not only invalidates any warranty but more importantly allows the internal controlled and isolated atmosphere to be contaminated by dust motes. The drive needs to be taken apart in a clean room.
Mechanical failures often present the most challenges to data recovery specialists. If the arm carrying the read-write heads (the component which accesses existing data and writes new data to the disk) crashes into the platters, a great deal of damage can be caused. This is known as a head crash.
Typically though, a head crash is quite a rare occurence and the drive will have some other type of mechanical failure. Data can be recovered in between 50% and 80% of cases of mechanical failure.
4. Logical errors
The term logical errors covers a spectrum of problems ranging from the very simple (eg. an invalid entry on the disk's file allocation table) to the extremely complex (eg. overwritten data caused by the incorrect usage of an imaging program). The success of data recovery procedures for this type of problem is dependent upon where the damaged or overwritten data is held on the platters, and how the incident occurred in the first place.
The four types of hard disk failure present different challenges to data recovery technicians. Some data recovery companies will claim to recover 100% of data from any type of failure, but unfortunately this is a dishonest assertion. Potential customers also need to be wary of "no fix, no fee" offers made by some companies. Their technicians would naturally be unwilling to spend time attempting complex recoveries which may not result in revenue and will therefore often dismiss the more difficult, but entirely possible, jobs as "unrecoverable". It is always advisable to get a second opinion if you have been told that your data cannot be retrieved.
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