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Data Recovery
In computing, data recovery is a process of retrieving deleted, inaccessible, lost, corrupted, damaged, or formatted data from secondary storage, removable media or files, when the data stored in them cannot be accessed in a usual way. The data is most often salvaged from storage media such as internal or external hard disk drives (HDDs), solid-state drives (SSDs), USB flash drives, magnetic tapes, CDs, DVDs, RAID subsystems, and other electronic devices. Recovery may be required due to physical damage to the storage devices or logical damage to the file system that prevents it from being mounted by the host operating system (OS). Logical failures occur when the hard drive devices are functional but the user or automated-OS cannot retrieve or access date stored in it. It can occur due to corrupt engineering chip, lost partitions, deleted data, firmware failure, failed formatting/re-installation. Data recovery can be a very simple or technical challenge. This is why there ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, engineering, mathematical, technological and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology and software engineering. The term "computing" is also synonymous with counting and calculating. In earlier times, it was used in reference to the action performed by mechanical computing machines, and before that, to human computers. History The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. Computing is intimately tied to the representation of numbers, though mathematical conc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Optical Disc Authoring Software
Optical disc authoring, including DVD and Blu-ray Disc authoring, is the process of assembling source material—video, audio or other data—into the proper logical volume format to then be recorded ("burned") onto an optical disc (typically a compact disc or DVD). Process To burn an optical disc, one usually first creates an optical disc image with a full file system, of a type designed for the optical disc, in temporary storage such as a file in another file system on a disk drive. One may test the image on target devices using rewriteable media such as CD-RW, DVD±RW and BD-RE. Then, one copies the image to the disc (usually write-once media for hard distribution). Most optical disc authoring utilities create a disc image and copy it to the disc in one bundled operation, so that end-users often do not know the distinction between creating and burning. However, it is useful to know because creating the disc image is a time-consuming process, while copying the imag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hard Disk Drive Platter
A hard disk drive platter (or disk) is the circular disk on which magnetic data is stored in a hard disk drive. The rigid nature of the platters in a hard drive is what gives them their name (as opposed to the flexible materials which are used to make floppy disks). Hard drives typically have several platters which are mounted on the same spindle. A platter can store information on both sides, requiring two heads per platter. Design The magnetic surface of each platter is divided into small sub-micrometer-sized magnetic regions, each of which is used to represent a single binary unit of information. A typical magnetic region on a hard-disk platter (as of 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 per square inch of disk area (15.5 Gbit/cm2). The material of the main ''magnetic medium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tape Drive
A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and a long archival stability. A tape drive provides sequential access storage, unlike a hard disk drive, which provides direct access storage. A disk drive can move to any position on the disk in a few milliseconds, but a tape drive must physically wind tape between reels to read any one particular piece of data. As a result, tape drives have very large average access times. However, tape drives can stream data very quickly off a tape when the required position has been reached. For example, Linear Tape-Open (LTO) supports continuous data transfer rates of up to 360 MB/s, a rate comparable to hard disk drives. Design Magnetic tape drives with capacities of less than one megabyte were first used for data storage on mainframe computers in the 1950s. , capaci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Head Crash
A head crash is a hard-disk failure that occurs when a read–write head of a hard disk drive makes contact with its rotating platter, slashing its surface and permanently damaging its magnetic media. It is most often caused by a sudden severe motion of the disk, for example the jolt caused by dropping a laptop to the ground while it is operating or physically shocking a computer. Head details A head normally rides on a thin film of moving air entrapped at the surface of its platter (some drives manufactured by Conner Peripherals in the mid-1990s used a thin liquid layer instead). The distance between the head and platter is called the flying height. The topmost layer of the platter is made of a Teflon-like material that acts like a lubricant. Underneath is a layer of sputtered carbon. These two layers protect the magnetic layer (data storage area) from most accidental touches of the read-write head. The disk read-and-write head is made using thin film techniques that in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CD-ROM
A CD-ROM (, compact disc read-only memory) is a type of read-only memory consisting of a pre-pressed optical compact disc that contains data. Computers can read—but not write or erase—CD-ROMs. Some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data (such as software or digital video) is only usable on a computer (such as ISO 9660 format PC CD-ROMs). During the 1990s and early 2000s, CD-ROMs were popularly used to distribute software and data for computers and fifth generation video game consoles. DVD started to replace it in these roles starting in the early 2000s. History The earliest theoretical work on optical disc storage was done by independent researchers in the United States including David Paul Gregg (1958) and James Russel (1965–1975). In particular, Gregg's patents were used as the basis of the LaserDisc specification that was co-developed between MCA and Philips after MCA purchased ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Encryption
In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decipher a ciphertext back to plaintext and access the original information. Encryption does not itself prevent interference but denies the intelligible content to a would-be interceptor. For technical reasons, an encryption scheme usually uses a pseudo-random encryption key generated by an algorithm. It is possible to decrypt the message without possessing the key but, for a well-designed encryption scheme, considerable computational resources and skills are required. An authorized recipient can easily decrypt the message with the key provided by the originator to recipients but not to unauthorized users. Historically, various forms of encryption have been used to aid in cryptography. Early encryption techniques were often used in military ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Espionage
Espionage, spying, or intelligence gathering is the act of obtaining secret or confidential information (intelligence) from non-disclosed sources or divulging of the same without the permission of the holder of the information for a tangible benefit. A person who commits espionage is called an ''espionage agent'' or ''spy''. Any individual or spy ring (a cooperating group of spies), in the service of a government, company, criminal organization, or independent operation, can commit espionage. The practice is clandestine, as it is by definition unwelcome. In some circumstances, it may be a legal tool of law enforcement and in others, it may be illegal and punishable by law. Espionage is often part of an institutional effort by a government or commercial concern. However, the term tends to be associated with state spying on potential or actual enemies for military purposes. Spying involving corporations is known as industrial espionage. One of the most effective ways to gath ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Forensics
Computer forensics (also known as computer forensic science) is a branch of digital forensic science pertaining to evidence found in computers and digital storage media. The goal of computer forensics is to examine digital media in a forensically sound manner with the aim of identifying, preserving, recovering, analyzing and presenting facts and opinions about the digital information. Although it is most often associated with the investigation of a wide variety of computer crime, computer forensics may also be used in civil proceedings. The discipline involves similar techniques and principles to data recovery, but with additional guidelines and practices designed to create a legal audit trail. Evidence from computer forensics investigations is usually subjected to the same guidelines and practices of other digital evidence. It has been used in a number of high-profile cases and is accepted as reliable within U.S. and European court systems. Overview In the early 1980s person ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File System Fragmentation
In computing, file system fragmentation, sometimes called file system aging, is the tendency of a file system to lay out the contents of files non-continuously to allow in-place modification of their contents. It is a special case of data fragmentation. File system fragmentation negatively impacts seek time in spinning storage media, which is known to hinder throughput. Fragmentation can be remedied by re-organizing files and free space back into contiguous areas, a process called defragmentation. Solid-state drives do not physically seek, so their non-sequential data access is hundreds of times faster than moving drives', making fragmentation a non-issue. It is recommended to not defragment solid-state storage, because this can prematurely wear drives via unnecessary write–erase operations. Causes When a file system is first initialized on a partition, it contains only a few small internal structures and is otherwise one contiguous block of empty space. This means that the fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
End User
In product development, an end user (sometimes end-user) is a person who ultimately uses or is intended to ultimately use a product. The end user stands in contrast to users who support or maintain the product, such as sysops, system administrators, database administrators, Information technology (IT) experts, software professionals and computer technicians. End users typically do not possess the technical understanding or skill of the product designers, a fact easily overlooked and forgotten by designers: leading to features creating low customer satisfaction. In information technology, end users are not "customers" in the usual sense—they are typically employees of the customer. For example, if a large retail corporation buys a software package for its employees to use, even though the large retail corporation was the "customer" which purchased the software, the end users are the employees of the company, who will use the software at work. Certain American defense-related pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
File Deletion
File deletion is the removal of a computer file, file from a computer's file system. All operating systems include commands for deleting files (rm (Unix), rm on Unix, del (command), era in CP/M and DR-DOS, del (command), del/del (command), erase in MS-DOS/PC DOS, DR-DOS, Microsoft Windows etc.). File managers also provide a convenient way of deleting files. Files may be deleted one-by-one, or a whole blacklist directory tree may be deleted. Purpose Examples of reasons for deleting files are: *Freeing the disk space *Removing duplicate or unnecessary data to avoid confusion *Making Information sensitivity, sensitive information unavailable to others *Removing an operating system or blanking a hard drive Accidental removal A common problem with deleting files is the accidental removal of information that later proves to be important. A common method to prevent this is to Backup, back up files regularly. Erroneously deleted files may then be found in archives. Another techniqu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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