Recovery 101: How do hard drives fail, what are the chances of recovery,
and other important questions answered.
The world of
data recovery is a big mystery for most consumers and even some
IT professionals. This is largely because hard drives themselves
are complex devices and their technological specifics are not generally
well known. Data recovery companies thrive on their customer’s
lack of information and often get away with charging obscene rates
for any recovery, regardless of complexity. We hope this article
will be a helpful resource for consumers and professionals alike.
We provide some basic information about data recovery by shedding
some light on how hard drives work, how they can fail, what are
the chances of successful recovery and how much you can expect to
pay for different types of data recovery.
about Hard Drives
A computer hard drive stores data on several metal oxide platters
which spin up to 10000 revolutions per minute. An actuator arm contains
the ‘head’ which reads and writes the data in the form
of magnetic charges one millionth of an inch above the surface.
Any given drive can have multiple read and write heads and each
head can ‘crash’ independently. A head crash occurs
when the read/write head comes in contact with the platters of the
disk (more on head crashes below). As manufacturers strive to increase
the amount of space on hard drives without increasing their physical
size, the data gets written increasingly closer together, making
for very difficult recovery should one or more heads crash. The
brain of the hard drive is its controller board and this is unique
for each individual hard drive. Finally, one other detail worth
a mention is the service track of a hard drive. This is an area
located on the outer part of the disk platter and it contains the
drive’s firmware zone. The firmware of a hard drive is the
information used by the computer to communicate correctly with the
drive. These are the main components that make a hard drive work,
now let’s talk about what can go wrong.
are many ways in which a hard disk can fail
Hard drives are extremely fragile and can suffer failures in many
different ways, leading to a loss of data. The five most common
types of failures are: logical failure, mechanical failure, electronic
failure, firmware corruption, and bad sectors. These are terms you
may have heard before, but were uncertain about what they really
mean. I’ll explain.
errors are often the simplest and sometimes the most difficult
problems to deal with when recovering data. They can range from
an invalid entry in a file allocation table, a simple problem that
needs little work; to severe issues such as the corruption or loss
of the entire file system. Logical errors can be spotted when files
become inaccessible, there is a delay in starting up the computer,
programs do not run, etc. Logical errors are often seen as simple
because there is nothing wrong with the physical drive leading users
to try recovering it themselves by using third party software. This
is quite risky, however, as running such software on a damaged drive
can result in total loss of data. The most effective way to prevent
logical errors on your hard drive is to regularly use the Disk Defragmentation
tool in your operating system.
a drive with logical errors can be simple and quick, however
if the problem requires manual bit-by-bit reconstruction of the
data, it can also be quite complex and time consuming. Normally,
logical errors are in the lower end of the price range as they do
not require manual disassembly of the drive, however there are cases
when logical failures end up in the higher end of the price range.
The bottom line with logical errors is the sooner they are caught
and the less a user tampers with the drive, the better the chances
for a quick and thorough recovery.
failures are often much more serious than any other failure and
frequently lead to a partial or even total loss of data.
The most common type of mechanical failure is called a head crash,
which is when the read/write head comes in contact with the disk
platter. Head crashes can be caused by a variety of reasons, including
physical shock, static electricity, power surges, and mechanical
read/write failure. Mechanical failures are detected by a constant
clicking or grinding noise coming from the drive. If you suspect
mechanical failure, you must immediately shut down your computer
and call us at 1.888.241.3282 for advice.
failures are usually the most severe and most challenging to recover
from. All mechanical failures require physical disassembly
of the drive. The replacement of a read/write head is one of the
most complex and costly procedures that can be performed by a data
recovery engineer, especially with larger capacity drives. The chances
of recovery depend entirely on how much damage the drive has sustained,
however they can be quite good. A crashed head does not mean that
all your data is lost! Once again, the sooner you catch a mechanical
problem and turn off your drive, the more of your precious data
is likely to be rescued.
failures are most common after a power surge or due to
some other electric problem, and the most common type is control
board failure. A power surge can knock out the control board, making
the drive undetectable in the BIOS. Because each drive is fitted
with a unique control board, recovery of this type is relatively
complex. However, the good news is that normally once the control
board issue is fixed, the data is usually 100% recoverable.
a drive that has suffered from an electronic failure can
be time consuming, mainly because the specific problem takes some
time to diagnose. Once diagnosed, though, the recovery is usually
not tremendously complex and would probably land in the mid-range
in terms of price. Most of the time, we are able to achieve a 100%
recovery from drives that have suffered an electronic failure.
corruption is caused by logical problems or physical damage
to the firmware zone on the disk platter. When the firmware becomes
corrupt, the computer is often unable to properly communicate with
the hard drive, and drive is not recognized in the BIOS. Fortunately,
when the drive fails due to firmware corruption, the data is usually
fully recoverable once the drive has been repaired.
a drive that has suffered from Firmware corruption is possible
with the use of our proprietary technology. Because the firmware
information is isolated on the outer rim of the disk, most of the
data can be recovered successfully. The complexity of recovering
a drive that has suffered from firmware corruption depends on the
amount of damage suffered by the service track on the disk’s
platter. Expect the cost of this type of recovery to be in the mid-
to high- price range.
sectors are a common fate of all hard drives. Eventually,
all drives develop areas that are no longer functional and when
this happens, they are isolated by the operating system. Bad sectors
are very much like bumps in the road, areas which are avoided by
the read/write head and which are no longer accessible to the user.
If mission critical data exists on the drive, we recommend to backup
as soon as possible, as the formation of bad sectors often indicates
the impending demise of the drive. Finally, and most importantly,
do NOT under any circumstances run the ScanDisk or Chckdsk utilities
when data becomes inaccessible. These utilities are designed to
fix only file system errors and not any other types of errors, so
if your hard drive has suffered from bad sectors, these utilities
only make things worse.
sectors are accessible
We are able to recover drives with bad sectors using our proprietary
mirroring technology. The process often involves manual mirroring
bit-by-bit, which can be time consuming. The price of this type
of recovery will generally be in the mid-range of the pricing
I hope the above
explanations are of some use to all computer users. The basic fact
is that data loss happens to everyone. Every hard drive crashes,
and often when you least expect it to. Backup is essential for end-users
and business users alike, and there are many excellent ways to back
up your data. But if you’ve lost data, attempt to understand
the problem before calling a data recovery company – think
of it as collaborating, not simply buying a service. At Accurate
Data Recovery, we strive to inform and educate our customers about
their data and hardware. We work together with the customer to recover
their files in a timely and efficient manner, while guaranteeing
the quality of our work.
Be informed, save your money, get your data back.
Accurate Data Recovery