Hard Disk Repair | DataRecoveryUnion.com

Disabling Auto-Relocation and SMART Attribute Processing

While the methods outlined in the previous section go a long way to obtaining an image of the data, other problems remain.

When drive firmware identifies a bad sector, it may remap the sector to a reserved area on the disk that is hidden from the user (Figure 3). This remapping is recorded in the drive defects table (G-list). Since the bad sector could not be read, the data residing in the substitute sector in the reserved area is not the original data. It might be null data or some other data in accordance with the vendor-specific firmware policy, or even previously remapped data in the case where the G-list was modified due to corruption.

Moreover, system software is unaware of the remapping process. When the drive is asked to retrieve data from a sector identified as bad, the drive firmware may automatically redirect the request to the alternate sector in the reserved area, without notifying the system before the error is returned. This redirection occurs despite the fact that the bad sector is likely still readable and only contains a small number of bytes with errors.

Figure 3: G-List Remapping
This process performed by drive firmware is known as bad sector auto-relocation. This process can and should be turned off before the imaging process begins. Auto-relocation on a drive with read instability not only obscures instances when non-original data is being read, it is also time-consuming and increases drive wear, possibly leading to increased read instability.

Effective imaging software should be able to turn off auto-relocation so that it can identify problem sectors for itself and take appropriate action, which ensures that the original data is being read.

Unfortunately, the ATA specification does not have a command to turn off auto-relocation. Therefore imaging software should use vendor-specific ATA commands to do this.

A similar problem exists with Self-Monitoring Analysis and Reporting Technology (SMART) attributes. The drive firmware constantly recalculates SMART attributes and this processing creates a large amount of overhead that increases imaging time and the possibility of further drive degradation. Imaging software should be able to disable SMART attribute processing.

Other drive preconfiguration issues exist, but auto-relocation and SMART attributes are among the most important that imaging software should address.

Increasing Transfer Speed with UDMA Mode

Modern computers are equipped with drives and ATA controllers that are capable of the Ultra Direct Memory Access (UDMA) mode of data transfer. With Direct Memory Access (DMA), the processor is freed from the task of data transfers to and from memory. UDMA can be thought of as an advanced DMA mode, and is defined as data transfer occurring on both the rise and fall of the clock pulse, thus doubling the transfer speed compared to ordinary DMA.

Both DMA and UDMA modes are in contrast to the earlier Programmed Input Output (PIO) mode in which the processor must perform the data transfer itself. Faster UDMA modes also require an 80-pin connector, instead of the 40-pin connector required for slower UDMA and DMA.

The advantages are obvious. Not only does UDMA speed up data transfer, but the processor is free to perform other tasks.

While modern system software is capable of using UDMA, imaging software should be able to use this data transfer mode on a hardware-level (bypassing system software) as well. If the source and destination drives are on separate IDE channels, read and write transfers can occur simultaneously, doubling the speed of the imaging process. Also, with the computer processor free, imaged data can be processed on the fly. These two advantages can only be achieved if the imaging software handles DMA/UDMA modes, bypassing system software. Most imaging tools currently available on the market use system software to access the drive and so don’t have these advantages.

Hard Disk Repair

Solve Disk Imaging Problems (Part 1)

DATARECOVERYUNION.COM16 years ago4 years ago38 mins

Imaging tools provide custom hardware and software solutions to the challenges of read instability.

Processing All Bytes in Sectors with Errors

While the system software works well with hard disk drives that are performing correctly, read instability must be dealt with using specialized software that bypasses the BIOS and operating system. This specialized software must be able to use ATA read commands that ignore ECC status. (These commands are only present in the ATA specification for LBA28 mode, though, and are not supported in LBA48.) Also, the software should have the capability of reading the drive error register (Figure 2), which the standard system software doesn’t provide access to. Reading the error register allows specialized software to employ different algorithms for different errors. For instance, in the case of the UNC error (“Uncorrectable Data: ECC error in data field, which could not be corrected”), the software can issue a read command that ignores ECC status. In many cases, the AMNF error can be dealt with in a similar way.

Bit 0 – Data Address Mark Not Found: During the read sector command, a data address mark was not found after finding the correct ID field for the requested sector (usually a media error or read instability).

Bit 1 – Track 0 Not Found: Track 0 was not found during drive recalibration.
Bit 2 – Aborted Command: The requested command was aborted due to a device status error.
Bit 3 – Not used (0).
Bit 4 – ID Not Found: The required cylinder, head, and sector could not be found, or an ECC error occurred in the ID field.
Bit 5 – Not used (0).
Bit 6 – Uncorrectable Data: An ECC error in the data field could not be corrected media error or read instability).
Bit 7 – Bad Mark Block: A bad sector mark was found in the ID field of the sector or an Interface CRC error occurred.

Figure 2: ATA Error Register

Only when the sector header has been corrupted (an IDNF error) is it unlikely that the sector can be read, since the drive in this case is unable to find the sector. Experience shows, however, that over 90 percent of all problems with sectors are due to errors in the data, not in the header, because the data constitutes the largest portion of the sector.

Also, the data area is constantly being rewritten, which increases read instability. Header contents usually stay constant throughout the life of the drive. As a result, over 90 percent of sectors that are unreadable by ordinary means are in fact still readable. Moreover, problem sectors usually have a small number of bytes with errors, and these errors can often be corrected by a combination of multiple reads and statistical methods.

If a sector is read ten times and a particular byte returns the same value eight times out of ten, then that value is statistically likely to be the correct one. More sophisticated statistical techniques can also be useful.

In fact, some data recovery solution providers have encountered situations in which every sector of a damaged drive had a problem. This situation would normally leave the data totally unrecoverable, but with proper disk imaging, these drives were read and corrected in their entirety.

Unfortunately, most imaging tools currently available on the market use system software to access the drive and are therefore extremely limited in their imaging capabilities. These products attempt to read a sector several times in the hope that one read attempt will complete without an ECC error. But this approach is not very successful. For example, if there is even a one percent chance of any byte being read incorrectly, the chances of reading all 512 bytes correctly on one particular read is low (about 0.58 percent). In this case, an average of 170 read attempts would be necessary to yield one successful sector read. As read instability increases, the chances of a successful read quickly become very low. For example, if there were a ten percent chance of reading any byte wrong, an average of 2.7 x 1023 read attempts would be needed for one successful one. If one read attempt took 1 ms, this number of reads would take 8000 billion years, or many times the age of the universe. No practical number of read attempts will give a realistic chance of success.

However, if imaging software can read while ignoring ECC status, a 10 percent probability of a byte being read in error is not an issue. In 10 reads, very few bytes will return less than seven or eight consistent values, making it virtually certain that this value is the correct one. Thus, imaging software that bypasses the system software can deal with read instability much more easily.

Hard Disk Repair

Disk Imaging Problems

DATARECOVERYUNION.COM16 years ago12 years ago08 mins

Disk imaging is not a trivial task. Degraded drives and drives whose physical defects have been repaired often yield a high read error rate, or read instability. Read instability means that multiple readings of the same data tend to yield different results each time. Read instability differs from cases where data originally written in error is read consistently each time, or where a physical scratch makes an entire part of the disk unreadable no matter how many read attempts are made.

What Causes Read Instability?

Repaired drives may have high read instability for a number of reasons. Donor parts, while nominally identical to the original failed parts, differ slightly due to tolerances in the manufacturing process. The majority of modern hard disk drives are individually tested at the factory and have optimized adaptive parameters burned into the read-only memory. If one or more parts are later replaced, the adaptive parameters are no longer optimized to the new configuration. Because modern drives are fine-tuned to obtain maximum performance and capacity, even small deviations from optimum can introduce a high rate of read errors.

In drives that have not been repaired, physical degradation due to normal use also means that adaptive parameters are no longer optimum, thus leading to read instability. For example, wear in the actuator bearings causes slight deviations in the distance the arm moves across the platter. As a result, the current that was once required to move the actuator to a certain track is no longer sufficient to move the arm precisely. Read errors can also be caused by dust infiltration into the disk drive over the course of its life, which may make the read process electronically noisy.

The important point is that failed drives tend to have read instability no matter what the reason for failure.

For the purposes of imaging a disk, read instability is not a major obstacle in principle, since each sector can be read several times and statistical methods can be applied to obtain the most likely correct value for each byte. However, because of the way that the basic input/output system (BIOS), operating system (OS), and drive firmware behave, it is impossible to obtain data during drive read instability without specialized hardware and software.

Why System Software Can’t Handle Read Instability

System software consists of a computer’s BIOS and OS. The primary reason that computers can’t handle read instability without specialized tools is that the system software reads each disk sector presuming that the sector is not corrupted—that is, that the data is read-stable. A sector on a disk typically consists of a header, 512 bytes of data, and error correction code (ECC) bytes (Figure 1). Other bytes are present to facilitate read/write synchronization.

For simplicity, the ECC bytes can be thought of as a checksum to validate data integrity. Most current hard disk drives are Advanced Technology Attachment (ATA) compliant devices. The system software reads the drive sector-by-sector, using the standard ATA read sector command. If a sector has a wrong ECC checksum, it returns no data, just an error, despite the fact that most of the bytes in the sector are likely correct and all are actually readable, even if some of the data is corrupt. The system software is unable to access data byte-by-byte, using other ATA read commands that read data regardless of ECC status.

Example of Sector Format.

The system software reads drives in this way because the mandate of computer architecture is to create a reliable, stable machine that runs at the highest possible speed. The system software cannot allow errors to be propagated from the hard drive to the computer’s random access memory (RAM). These errors might be part of an executable file that would then cause the computer to stop responding. Thus, system software has a low tolerance for read instability and assumes that the drive is working correctly without delving into drive errors except to flag whole sectors as bad and to avoid reading them.

Also, in many cases the system software is unable to handle drive errors, a situation that may cause the system to stop responding.

Using the system software to read a drive is also time-consuming and involves intense drive processing, leading to further wear. This wear increases the likelihood of further disk degradation during the imaging process. See “Processing All Bytes in Sectors with Errors ” for more information on how disk imaging is by its nature very demanding on the drive, involving multiple reads on the entire disk and modifying its firmware data. Since progressive disk degradation is common (that is, read instability increases with use), it is desirable to reduce the
demands on the drive.

Thus, even a relatively low level of read instability, which is common for drives in recovery, can lead to the computer not being able to read the drive at all, despite the fact that the drive is still readable by other means.

Hard Disk Repair

Ultimate Boot CD

DATARECOVERYUNION.COM16 years ago2 years ago03 mins

You need the Ultimate Boot CD if you want to:

Run floppy-based diagnostic tools from CDROM drives. More and more PCs are shipped without floppy drives these days, and it is such a royal pain when you need to run diagnostic tools on them.
Free yourself from the slow loading speed of the floppy drive. Even if you do have a floppy drive, it is still much much faster to run your diagnostic tools from the CDROM drive, rather than wait for the tool to load from the floppy drive.
Consolidate as many diagnostic tools as possible into one bootable CD. Wouldn’t you like to avoid digging into the dusty box to look for the right floppy disk, but simply run them all from a single CD? Then the Ultimate Boot CD is for you!
New! Run Ultimate Boot CD from your USB memory stick. A script on the CD prepares your USB memory stick so that it can be used on newer machines that supports booting from USB devices. You can access the same tools as you would from the CD version.

Ultimate Boot CD is completely free for the download, or could be obtained for a small fee. If you had somehow paid a ridiculous amount of money for it, you have most likely been fleeced. The least you could do is to make as many copies of the offical UBCD and pass it to your friends, relatives, colleagues or even complete strangers to minimize the per unit cost of your loss!

When you boot up from the CD, a text-based menu will be displayed, and you will be able to select the tool you want to run. The selected tool actually boots off a virtual floppy disk created in memory.

Hard Disk Repair

Glossary of Hard Disk Drive Terminology (Letter E)

DATARECOVERYUNION.COM16 years ago12 years ago03 mins

ECC On-the-Fly
A hardware correction technique that corrects errors in the read buffer prior to host transfer without any performance penalties. These error corrections are invisible to the host system because they do not require assistance from the drive’s firmware.

EIDE (Enhanced Integrated Drive Electronics)
The primary interface used by desktop PCs to handle communication between hard drives and the central processing unit. The equivalent interface system in most enterprise systems is SCSI.

Embedded Servo Control
The embedded servo control design generates accurate feedback information to the head position servo system without requiring a full data surface (which is required with a “dedicated” servo control method) because servo control data is stored on every surface.

Encoding
The process of modifying data patterns prior to writing them on the disk surface.

Enterprise
The series of computers employed largely in high-volume and multi-user environments such as servers or networking applications; may include single-user workstations required in demanding design, engineering and audio/visual applications.

Enterprise Storage Group
The Western Digital operation that designs, produces and markets hard drives for the enterprise market.

Error Correction Code (ECC)
A mathematical algorithm that detects and corrects errors in a data field.

Error Log
A record that contains error information.

Error Rate
The number of errors of a given type that occur when reading a specified number of bits.

Extended Partition
You can create multiple partitions on a hard disk, one primary partition and one or more extended partition(s). Operating system files must reside on the primary partition. An extended partition is a partition where non-system files (files other than DOS or operating system files) can be stored on a disk. You can also create logical drives on the extended partition.

Hard Disk Repair

Glossary of Hard Disk Drive Terminology (Letter D)

DATARECOVERYUNION.COM16 years ago12 years ago04 mins

Database
A collection of data stored on a computer system medium, such as a hard drive, CD-ROM, etc., that can be used for more than one purpose.

Data Lifeguard
A Western Digital exclusive data reliability feature that automatically detects, isolates and repairs problem areas on the hard drive before data loss can occur.

Data Synchronizer
An electronic circuit that uses a clock signal to synchronize data to facilitate interpretation.

Dedicated Landing Zone
The designated radial zone of the disk, usually at the inner portion of the disk, where the heads are stored to avoid contact with the data cylinders when power to the drive is off.

Defect Free
A term used to describe recording surfaces that have no detectable defects.

Defect Management
A general methodology of eliminating data errors on a recording surface by mapping out known defects on the media. The defective areas are rendered inaccessible, so that when information is written to the disk, it is stored to non-defective locations on the disk.

Desktop
A personal computer sized to fit on or under your desktop. Western Digital EIDE hard drives are designed to fit into a desktop PC.

Differential SCSI
An electrical signal configuration which uses pairs of lines for data transfer. Used primarily in applications requiring long cable lengths of up to 82 feet (25 meters).

Direct Memory Access (DMA)
A process for transferring data directly to and from main memory, without passing through the CPU. DMA improves speed and efficiency by allowing the system to continue CPU processing even while it is transferring data to/from the hard drive.

Disk
A rigid platter, usually constructed of aluminum or mylar, with a magnetic surface that allows the recording of data, that is stored inside the drive.

Disk Controller
The chip or circuit that controls the transfer of data between the disk and buffer. (See also disk drive controller and interface controller).

Disk Drive Controller
The hard disk drive controller electronics which include the disk controller and the interface controller. (See also disk controller and interface controller.)

Disk Operating System (DOS)
The computer program that controls the organization of data, files and processes on the computer.

Disk Transfer Rate
Speed at which data transfers to and from the disk media (actual disk platter); a function of the recording frequency. Typical units are bits per second (BPS), or bytes per second. Hard drives have an increasing range of disk transfer rates from the inner diameter to the outer diameter of the disk.

Distribution Channel
Electronics distributors and certain retail chains that deliver electronic goods to end users through value-added resellers and some retail stores.

Hard Disk Repair

Glossary of Hard Disk Drive Terminology (Letter C)

DATARECOVERYUNION.COM16 years ago12 years ago07 mins

Cable Select (CSEL)
An alternative option which can be used in place of setting Master/Slave jumpers in the designation of drives in a dual drive configuration. Master/Slave designation is based on the position of the drives relative to the cable. Special cabling is required by the system manufacturer to selectively ground the CSEL signal on one of the IDE cable connectors. For example, when one of the drives is connected to the grounded CSEL conductor, it configures itself as the Master. When the second drive is connected to the other connector, on which CSEL is not grounded, it becomes the slave. This eliminates the need for unique jumpering configurations between the Master and Slave drives.

Cache
High-speed RAM used as a buffer between the CPU and a hard drive. The cache retains recently accessed information to speed up subsequent accesses to the same data. When data is read from or written to disk, a copy is saved in the cache, along with the associated disk address. The cache monitors the addresses of subsequent read operations to see if the required data is already in the cache. If it is, the drive returns the data immediately. If it is not in the cache, then it is fetched from the disk and saved in the cache.

Capacity
The amount of information, measured in bytes, that can be stored on a hard drive. Also known as storage capacity.

Channel
A connection or socket on the motherboard or controller card. A motherboard may have one or two channels (primary and secondary). If your motherboard has only one channel, you may need to add a controller card to create a secondary channel.

Channel Assembly
In the computer industry, the final assembly of a system by a distributor or reseller from kits provided by the manufacturer and from components shipped directly to the assembler by subsystem makers.

Clean Room
An environmentally controlled, dust-free, assembly or repair facility in which hard drives are assembled or opened for internal servicing.

Cluster
A cluster is defined as an allocation unit. At least one cluster is allocated to each file, regardless of the file’s size, that is stored in the DOS environment. The cluster size increases with the partition size determined during formatting. With a 1024 MB partition, the cluster size is 32 KB. Each file stored consumes 32 KB of storage space, no matter how small the file. Create multiple, smaller partitions to avoid wasting space on small files. (This definition applies to FAT16).

CMOS Setup
A program supplied in most systems that allows you to configure internal and external devices.

Command Aging
A SCSI feature that prevents the command reordering algorithm from keeping I/O processes waiting in the command queue for extended periods of time.

Command Queuing
A feature that enables the drive to receive I/O processes from one or more initiators and execute them in an optimum sequence.

Command Reordering
A feature that allows the drive to reorder I/O processes in the command queue, which results in minimizing the seek time and rotational latency and thus increases throughput.

Controller
See disk controller, interface controller, and disk drive controller.

Controller Card
An adapter with the control electronics for one or more hard drives. Usually installed in a bus slot in the computer.

Correctable Error
An error that the drive can correct by using Error Detection and Correction schemes.

Customer Configuration Code (CCC)
A firmware revision tracking code that defines a major product change. This number increments as form, fit or function changes are implemented. The CCC code guarantees that the correct revision of drive product is provided to the customer.

Cyclic Redundancy Check (CRC)
Data stored or transmitted with data to detect corruption. By calculating the CRC data and comparing it to the original data sent, the receiver can detect some types of transmission errors.

Cylinder
The cylindrical surface formed by identical track numbers on vertically stacked disks.

Cylinder, Head, Sector (CHS) Addressing
A method of referencing the sectors on a drive as a collection of unique cylinder, head and sector addresses. Each block on the drive will have a unique cylinder, head and sector address.

Hard Disk Repair

Glossary of Hard Disk Drive Terminology (Letter B)

DATARECOVERYUNION.COM16 years ago12 years ago04 mins

Bandwidth
The amount of data that can be sent over a given circuit. See also buffer bandwidth.

BIOS (Basic input/output system)
A program or set of programs that control the basic functions of the computer.

Bit
An abbreviation for a binary digit which can be either 0 or 1. A bit is the basic data unit of all digital computers. It is usually part of a data byte, or data word; however, a single bit can be used to control or read logic ON/OFF functions. A bit is a single digit in a binary number. Bits are the basic unit of information capacity on a computer storage device. Eight bits equal one byte.

Bit density
Expressed as bits per inch (BPI), the number of bits that can be written onto one inch of track on a disk surface.

Block
A group of bytes handled, stored, and accessed as a logical data unit, such as an individual file record. A block in UNIX workstation environments is the smallest contiguous area that can be allocated for the storage of data. (Note: A different definition of the term is used when referring to the physical configuration of a hard drive.)

Boot
To start or restart your computer; loading the operating system.

BPI
Bits per inch. Indicates the density of information on a hard drive. See bit density.

Buffer
A temporary data storage area used to make up for a difference in data transfer rates and/or data processing rates between sender and receiver. For example, a printer buffer copies data from the computer and holds it until the printer is ready to print it.

Buffer Bandwidth
The speed of transferring data to or from the buffer.

Build-to-order
In the computer industry, the assembly of a system in response to a customer’s order, rather than for inventory or mass shipment. A system utilized by Dell Computer and Gateway, now being emulated to some degree by other PC makers like IBM, HP and Compaq.

Business Model
A company’s financial plan, including product pricing and margin calculations.

Burst Mode Transfer Rate
The transfer rate into the buffer RAM of the hard disk. This rate does not factor in delays due to latencies or host delays. See also transfer rate.

Bus
The path that carries data between the computer (microprocessor) and peripheral devices. An IDE interface cable and a SCSI cable are both examples of a bus.

Byte
A sequence of eight binary digits or bits regarded to be a unit or binary word. The storage capacity of a disk drive is commonly measured in megabytes, which is the total number of storable bits divided by eight million.

Hard Disk Repair

Glossary of Hard Disk Drive Terminology (Letter A)

DATARECOVERYUNION.COM16 years ago12 years ago05 mins

Access
Retrieval of data from or transfer of data into a storage device or area such as RAM or a register.

Access Time
The amount of time, including seek time, latency and controller time, needed for a storage device to retrieve information.

Active Partition
The partition of the drive that contains the operating system. If the drive has multiple partitions, only the primary partition can be made active. A hard drive can have only one active partition.

Active Termination
One or more voltage regulators that produce termination voltage. The voltage regulator(s) drive a constant voltage along the bus to ensure that the data signal stays constant and strong over the entire length of the bus. The result is increased data integrity and reliability.

Actuator
A mechanical assembly that positions the read/write head over the appropriate track.

Actuator Arm
The part of the actuator assembly that includes the positioning arm and the read/write heads.

Adaptive Caching
A feature of Western Digital drives that enables them to improve performance and throughput by adapting to the application being run.

Address
In the hard drive industry, there are several types of addresses; an address may refer to that of a drive, called a unit address; radial position, called a cylinder address; or circumferential position, referred to as a sector address.

AFR
Annualized Failure Rate.

Allocation
The method DOS uses to assign a specific area of the hard drive to a given file. (See also cluster.)

American National Standards Institute (ANSI)
A governmental body of the United States responsible for approving US standards in many areas, including computers and communications. ANSI is a member of the International Standards Organization (ISO).

Arbitrated Loop
Fibre channel topology where two or more ports can interconnect but only two ports can communicate at the same time.

Arbitration
The act of determining which command, device, or communication protocol controls the operating environment.

Areal Density
The number of bits of data that can be recorded onto the surface of a disk or platter usually measured in square inches. The areal density is calculated by multiplying the bit density (BPI – Bits Per Inch) by the track density (TPI – Tracks Per Inch).

ASP
Average selling price.

Asynchronous Transmission
Each byte of information is synchronized individually through the use of request and acknowledge signals.

AT Bus Attachment (ATA-4)
The interface defined by IBM for the original AT disk controller. Western Digital designed the WD Caviar® drives to be fully ATA-4 compatible.

Auto Defect Retirement
If the drive finds defective sectors during reads or writes, they are automatically mapped out and relocated.

Auto Park
Turning off the drive power causes the drive to move the read/write heads to a safe non-data landing zone and lock them in place.

Average Access Time
The average length of time a drive takes to perform seeks, usually measured with 1/3 stroke.

Average Seek Time
Length of time it takes the drive to move the read/write heads to a safe non-data landing zone and lock them in place.

Hard Disk Repair

Data Recovery Equipment

DATARECOVERYUNION.COM16 years ago4 years ago06 mins

Today computer is being an integral and indispensable part in IT world. No matter what is your line, finance, education, business consulting and investigation, IT information security, or else. In fact, most people always take it for granted. You should never brag your computer can be failure-free.

The foremost use of computer is data storage. All the data is stored on a physical disk named hard disk drive which is a magnetic layer. And it is more likely to be stricken of any time by a wide variety of reasons, such as a partition lost, system can not access, human mistake (accidental reformatting, delete), file corruption, power surge, and virus attack, to the worst, these physical level failures typically are head crash, platter scratch, and motor failures caused by overwriting, physical damages, natural disasters, etc.

Sometimes a hard drive has been stricken dead or not working at all without any warning signs, but some other times there may be some clues that something is going bad or amiss. Such changes in performance or sudden blue screens are telltale signs that the hard drive may be on its way to collapse. The most obvious and common sign are clicking, squealing, scraping or grinding noises.

The computer become more involved in our daily life, so the danger of data loss also surfaces.

As most of us have already experienced data loss, it could be frustrated and traumatic, when you finally find your critical data are not able to recover. As a matter of fact, logical failures as I previously mentioned, a data recovery software program can simply work them out, but if more, No! Those drives with minor physical failures will need special equipment to repair hard drive or recover data.

Why data recovery software programs will stop there? The ordinary user-level repeated-read access method that used by imaging software bring a risk of damaging the disk and head, making data lost irretrievable. Also the software skips bad sectors directly in order not to get hang. Even so it gets hang most of the time in case the drive has lost of bad sectors. Still there is no guarantee that all the data will be extracted as much as possible, although days or weeks of time wasted on imaging bad drives. That’s why you should avoid it at all cost.

With a unique data recovery equipment known as Data Compass which is mostly used among experts and practitioners worldwide where traditional tools can not reach the height. DC reads data of each sector physically byte-to-byte, including good and bad, and copied to a good disk using its data extraction software and hardware. A ShadowDisk technology allows DC to maximally avoid second damaging drives.

However, we hardly figure out how much data normally can be recovered. It all depends. In most cases, data will be able to recover as long as the parts of hard drive are not severely damaged. Otherwise you should swap its components then are platters, heads, and a spindle motor.

A current tool HD HPE PRO used to open hard drive will be replaced by HPE SP. The new product is the offspring of the old one; what’s more, a brand new designed platter exchanger allows users to work on hard drives with spacers between platters. HPE SP is made of metal alloy and has had both quality and stability improved. If you have already known about data recovery, you can be an expert with the very option. Of course, you can go and find an expert elsewhere to fix your drives, if the extra expenditure is not a problem anyway.