What Is Data Recovery?
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What Is A Hard Disk?
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What Is A Hard Disk Platter?
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What Are Read / Write Heads?
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What Is Physical Damage?
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What Is Logical Damage?
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Diagnosing Your Drive(s)?
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Recovering Your Data?
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Can Any Data Be Recovered?
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How Can I Prevent Data Loss?
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Is My Data Secure?
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Which Drive(s) Performs Best?
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Should I Open My Hard Drive?
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How Should I Pack My Drive?
What Is Data Recovery?
Data Recovery is the process of salvaging data from damaged, failed,
corrupted or inaccessible primary storage media when it cannot
be accessed normally. Often the data is being salvaged from storage
media formats such
as hard disk drives, storage tapes, CDs, DVDs, RAIDs, and other
electronics. This can be due to physical damage to the storage device
or logical damage
to the file system, that prevents it from being mounted by the
host operating system. Although there is some confusion as to the
term, Data Recovery
can also be the process of retrieving and securing deleted information
from a storage media for forensic purposes.
What Is A Hard Disk?
A hard disk drive commonly known as a (HDD) or hard drive (HD)
and formerly known as a fixed disk, is a non-volatile storage
device which stores digitally encoded data on rapidly rotating platters
with
magnetic
surfaces. In theory, "drive" refers
to a device that drives (removable) media, such as a tape drive or (floppy)
disk drive, while a hard disk contains fixed (non-removable) media. However,
in recent times, the hard disk drive has become more commonly known as
the "hard drive".
Hard disks were originally developed for use with computers. In the 21st century, applications for hard disks have expanded beyond computers to include, digital video recorders, digital audio players, personal digital assistants and digital cameras. In 2005 the first mobile phones to include hard disks were introduced by the Samsung Group and Nokia. The need for large-scale, reliable storage, independent of a particular device, led to the introduction of configurations such as RAIDs, hardware such as network attached storage (NAS) devices, and systems such as storage area networks (SANs) for efficient access to large volumes of data.
What Is A Hard Disk Platter?
A hard disk platter (or disk) is a component of a hard disk drive,
it is the circular disk on which the magnetic data is stored. The
rigid nature of the platters in a hard disk drive is what gives them
their name
(as opposed to the flexible materials which are used to make floppy
disks). Hard disk drives typically have several platters which are
mounted on the
same spindle. The magnetic surface of each platter is divided into
small sub-micrometre-sized magnetic regions, each of which are used
to represent
a single binary unit of information.
A typical magnetic region on a hard disk platter (in 2006) is about 200-250 nanometers wide, (in the radial direction of the platter) and extends about 25-30 nanometers in the down-track direction (the circumferential direction on the platter), corresponding to about 100 billion bits (Gigabits) per square inch of disk area. The material of the main magnetic medium layer is usually a cobalt-based alloy. In today's hard disk drives each of these magnetic regions is composed of a few hundred magnetic grains, which are the base material that gets magnetized. However, future hard disk drives may use different systems to create the magnetic regions. As a whole, each magnetic region will have a magnetization.
What Are Read / Write Heads?
Hard disk read/write heads are mechanisms that read data from or
write data to disk drives. The read/write heads have gone through
a number
of changes over the years. In a hard disk drive, the read/write
heads 'fly' above the
disk surface with clearance of as little as 3 nanometres. The "flying
height" is constantly decreasing to enable higher areal density. The flying height of
the head is controlled by the design of an air-bearing etched onto
the disk-facing surface of the slider.
The role of the airbearing is to maintain the flying height constant as the head moves over the surface of the disk. If the head hits the disk's surface, a catastrophic head crash can result.The heads themselves started out similar to the heads in tape recorders, simple devices made out of a tiny C-shaped piece of highly magnetizable material called ferrite wrapped in a fine wire coil. When writing, the coil is energized, a strong magnetic field forms in the gap of the C, and the recording surface adjacent to the gap is magnetized.
When reading, the magnetized material rotates past the read/write heads, the ferrite core concentrates the field, and a current is generated in the coil. The gap where the field is very strong is quite narrow. That gap is roughly equal to the thickness of the magnetic media on the recording surface. The gap determines the minimum size of a recorded area on the disk. Ferrite heads are large, and write fairly large features. They must also be flown fairly far from the surface thus requiring stronger fields and larger heads.
What Is Physical Damage?
A wide variety of failures can cause physical damage to storage
media. CD-ROMs can have their metallic substrate or dye layer scratched
off, hard
disk drives can suffer any number of mechanical failures, such
as head crashes and failed motors, physical damage always causes
at least some
data loss, and in many cases the logical structures of the file
system are damaged as well. This causes logical damage that must
be dealt with
before any files can be salvaged from the failed media.
Most physical damage cannot be repaired by end users. For example, opening a hard disk drive in a normal environment can allow dust to settle on the surface, causing further damage to the platters and complicating the recovery process. Furthermore, end users generally do not have the hardware or technical expertise required to make these repairs, therefore, costly Data Recovery companies are consulted to salvage the data.
The extracted raw data can be used to reconstruct usable data after any logical damage has been repaired. Once that is complete, the files may be in usable form although recovery is often incomplete. On the other hand, there are many accounts of users getting a bad disk going long enough to pull their data off, often via slightly bizarre tricks. These include making the drive cold (in the freezer) or spinning it manually on the ground, both actions being used unstick a jammed platter.
Examples of physical recovery procedures are, removing a damaged PCB (printed circuit board), changing the original damaged read/write head assembly, removing the hard disk platters from the original damaged drive and installing them into a healthy drive, and often a combination of all of these procedures. All of the above described procedures are highly technical in nature and should never be attempted by an untrained individual. All of these procedures will almost certainly void the manufacturer's warranty. Data Recovery is also possible from digital media such as flash cards used in digital cameras etc.
What Is Logical Damage?
Far more common than physical damage is logical damage to a file
system. Logical damage is primarily caused by power outages
that prevent file system
structures from being completely written to the storage medium,
but problems with hardware (especially RAID controllers) and
drivers, as well as system
crashes, can have the same effect.
The result is that the file system is left in an inconsistent state. This can cause a variety of problems, such as strange behavior (e.g., infinitely recursing directories, drives reporting negative amounts of free space), system crashes, or an actual loss of data. Various programs exist to correct these inconsistencies, and most operating systems come with at least a rudimentary repair tool for their native file systems.
Two main techniques are used to repair programs. The first, consistency checking, involves scanning the logical structure of the disk and checking to make sure that it is consistent with its specification. For instance, in most file systems, a directory must have at least two entries, a dot (.) entry that points to itself, and a dot-dot (..) entry that points to its parent. A file system repair program can read each directory and make sure that these entries exist and point to the correct directories. If they do not, an error message can be printed and the problem corrected. Both chkdsk and fsck work in this fashion. This strategy suffers from two major problems. First, if the file system is sufficiently damaged, the consistency check can fail completely. In this case, the repair program may crash trying to deal with the mangled input, or it may not recognize the drive as having a valid file system at all. The second issue that arises is the disregard for data files. If chkdsk finds a data file to be out of place or unexplainable, it may delete the file without asking. This is done so that the operating may run smoother, but the files deleted are often important user files which can not be replaced. Similar issues arise when using system restore disks (often provided with proprietary systems like Dell and Compaq), which restore the operating system by removing the previous installation. This problem can often be avoided by installing the operating system on a separate partition from your user data.
The second technique for file system repair is to assume very little about the state of the file system to be analyzed, and using any hints that any undamaged file system structures might provide, rebuild the file system from scratch. This strategy involves scanning the entire drive and making note of all file system structures and possible file boundaries, then trying to match what was located to the specifications of a working file system. Some third-party programs use this technique, which is notably slower than consistency checking. It can, however, recover data even when the logical structures are almost completely destroyed. This technique generally does not repair the underlying file system, but merely allows for data to be extracted from it to another storage device.
While most logical damage can be either repaired or worked around using these two techniques, data recovery software can never guarantee that no data loss will occur. For instance, in the FAT file system, when two files claim to share the same allocation unit ("cross-linked"), data loss for one of the files is essentially guaranteed. Some kinds of logical damage can be mistakenly attributed to physical damage. For instance, when a hard drive's read/write head begins to click, most end-users will associate this with internal physical damage. This is not always the case. Often, either the firmware on the platters or the controller card will instead need to be rebuilt. Once the firmware on either of these two devices is restored, the drive will be back in shape and the data accessible.
Diagnosing Your Drive(s)?
Once DiskFlow receive your hard disk drive(s) it will be logged
into our system and queued for diagnosis by one of our Data Recovery
engineers.
The Data Recovery process is split into two stages, a diagnosis
stage and a recovery stage. At the diagnosis stage our experienced
engineers will diagnosis
the problem with your media and try to obtain a directory and file
listing.
DiskFlow will then forward this to the customer with the forecasted cost of recovery. The customer then has the opportunity to have the recovered data for that amount and see what they will be charged before any work is carried out. DiskFlow will provide you with an initial diagnosis, total recovery cost and estimated completion date within 24 hrs of receiving your hard disk drive(s).
Recovering Your Data?
On our priority Standard service at DiskFlow, our diagnosis and
recovery will take between three to five days. DiskFlow also accommodate
a Fast Track
service where work is carried out continuously during office hours,
and an Emergency service where work is carried out continuously outside
of office
hours if required, on weekends and bank holidays.
Recovery time for all DiskFlow's services will depend entirely on the severity of the fault and how much work is required to recover your data. (At no time is the integrity of your data placed in jeopardy as all recovery procedures are performed on an exact sector by sector duplicate of your original drive).
Can Any Data Be Recovered?
When working on any computer system we generally face situation's
where files are accidentally deleted, accidental formatting of the
whole operating
system, virus attacks which leads to loss of data. Data Recovery
can also be the process of recovering deleted information from a
storage media.
DiskFlow are experts in salvaging data from inaccessible, formatted, damaged, failed, or damaged primary storage media where data cannot be accessed normally using operating systems. DiskFlow has the highest success rate within the Data Recovery industry, DiskFlow are specialist in recovering data loss caused due to power surges, static electricity, lightening strikes, fires, floods, sabotage, viruses, accidents, and user error (i.e. deleted files and formatted hard disk drives). DiskFlow rescue data from data storage media such as hard disk drives, tapes, pen drives, mobile phones, digital medias, CDs, DVDs, RAIDs and other optical medias.
If a drive has suffered crash damage, or its read/write head's have come in contact with the disk platters, data lost will be unrecoverable in most cases. If the disk platters are physically damaged in any way or form and the magnetised layer on the disk platter is damaged it is extremely difficult to recover any meaningful data at this stage. After a successful Data Recovery, sometimes many files tends to get corrupted and are inaccessible due to high interpretation of the data during the Data Recovery Process.
How Can I Prevent Data Loss?
Unfortunately through years of experience DiskFlow have found there
is no way of preventing data loss, therefore there is no guarantee
that data stored in a single place will remain unharmed forever.
The reality is that
disks and tapes are going to fail at some point in their lives,
and you must be prepared for it. Backing up your data on a regular
basis is essential,
and spending a few hours to make sure your data is safe, is much
better than hours of panic waiting for the recovered data to be returned
(If recoverable).
A reliable and well-known anti-virus package is also recommended,
and it should be frequently updated by the manufacturer to provide
protection against
the latest virus threats.
Is My Data Secure?
At DiskFlow keeping your data secure is a very high priority for
us. For major corporations we have signed many non-disclosure agreements.
With
or without an agreement, DiskFlow treat your data with the utmost
confidentiality. DiskFlow operates within a secure environment so
that you can rest easy
knowing that your information is kept private and safe at all
times.
All members of DiskFlow are under non-disclosure. The diagnosis and recovery process is conducted in secure labs with controlled access to ensure the confidentiality of your data. DiskFlow have unwritten non-disclosure agreements with all of our customers, but if you require a written agreement it can be faxed to us for processing.
Which Drive(s) Performs Best?
When purchasing a storage device, it is important to understand
what features it has and how it suits your intended application.
Some hard disk
drives are faster, some are more reliable, and many drives can
vary dramatically in price. Over the last few years, the reliability
and capacity of hard disk
drives has dramatically increased to meet the demands of powerful
and storage hungry applications. Disk technology is changing constantly
on a daily basis,
and it may be frustrating when trying to buy a new drive.
Should I Open My Hard Drive?
DiskFlow recommend NOT opening a hard disk drive, as this requires
special tools, skills, and a clean environment. Even the slightest
particle of dust could cause harm to a disk platter, and disturbing
a case screw could
result in damage to the hard disk drive itself. Under no circumstances
should a hard disk drive be opened in a normal atmosphere with standard
tools. It
may cause irreversible harm to the data stored on the hard disk
drive, and will damage the hard disk drive.
How Should I Pack My Drive?
Normal Hard Disk Drives.
DiskFlow recommend that all hard disk drives sent to us are packaged ideally within a hard disk drive box, which shall protect the hard disk drive during shipment.
DiskFlow suggest the hard disk drive is wrapped in an anti-static electro-static discharge (ESD) bag before being placed in the shipping box. (If an anti-static bag is not available, use a freezer bag which is sufficient). Any packaging such as bubble wrap, anti-static foam or shredded paper will also help cushion the hard disk drive through the shipment process.
DiskFlow recommend packing the hard disk drive in a sturdy corrugated cardboard box twice the size of the hard disk drive, with heavy anti-static foam padding, bubble wrap, shredded paper or other anti-vibration materials. Do not use Styro foam as this attracts static electricity.
If possible use thick foam rubber, supporting all four sides of the hard disk drive, enclosed in a corrugated cardboard box which is typically considered good packaging. (The padded material should be at least two inches thick around the hard disk drive).
Water Damaged Hard Disk Drives.
If your hard disk drive has suffered water damage, please do not dry it. Enclose the hard disk drive along with a damp sponge in a sealed plastic bag to prevent it from drying out. Recovery is more likely if our engineers receive the hard disk drive before it has dried out completely, otherwise further damage may occur.
Controller Boards.
When recovering from older models, we may need you to send the controller along with the hard disk drive. Please remove the controller carefully, enclose in an anti-static material and ship along with the hard disk drive.
Should you require further assistant regarding the packaging process please contact DiskFlow before any media is sent to us, so we can ensure the correct delivery procedure is followed.
