D ‐ Data Recovery Glossary Database – a compilation of data on a computer drive and in a compatible format. This data is organized in a way that it can be used to serve as information in its field of relevance. For example, list of hotels that have vacancies are the database which is presented to users when they search for availability of rooms in a hotel. Data synchronizer – a clock signal that is synchronous with incoming files or data is produced by an electronic circuit, and the signal is used to decode the information being received. The circuit itself acts as a synchronizer; for example, apps and mobile phones are kept in sync constantly by the electronic circuit. Data transfer rate – the speed at which electronic data stored in one device travels to another device through some form of connectivity. It is measured in megabits or megabytes of data sent per second. When some data is transferred within one hard drive, it is called data transfer to disk, and the rate is expressed as megabits per second (Mbps). When data is sent from the buffer to the host party, it is expressed as megabytes per second (MBps). Dedicated servo – a disk that contains no other user‐related data is kept for the purpose of embedding position signals that contain specific information. This information is used to position the read or write heads. A servo writer is used to write these control signals which cannot be reproduced if an error occurs. Dedicated landing zone – it is the area of the hard disk inside a computer system that has no other data stored on it. This area is used by the read/write heads when the system is inactive. This zone also makes sure that the hard disk is not physically damaged while it is being handled by the user or when data is stored on it. This magnetized area has no contact with the surrounding objects to prevent damage. Defect free – when recording devices are referred to using this term, it means that they have not been diagnosed with an internal or apparent defect or damage. Defect management – when a defect is detected on a recording device, such as a disk drive, measures to eliminate those defects are known as defect management. This is done by either fixing the defect or rendering it inaccessible so that data storage on the device is done without hassle. The information written on the disk is allocated to areas that are free of defects or will not be harmed by the hidden corrupt files. Defragment – it is a process used to decrease the amount of fragments produced in a storage medium such as a hard drive. This process is complete once the files on the
storage device are re‐organized and the least number of fragments is reached. More free space results in the disk once this is followed by” compacting” the disk drive in order to inhibit the formation of more fragments. As we mount up data on storage drives, they become loaded with non‐contiguous blocks. One file gets scattered across the whole drive and performance of the system becomes weak. This is the point where defragmentation helps. Storage media should undergo this process as soon as fragmentation level reaches 10%. Desktop – it is a personal computer system designed to fit the top of a desk. It can be used in a fixed location only, unlike laptops that are mobile devices. Modern designs stand upright on a desk and have been infused with latest features. Differential SCSI – it is an electronic configuration that makes use of dual lines for the transfer of data. It is used for devices demanding long cable connections of up to 25 meters. An SCSI connector has either 50 pins (8‐bit system) or 68 pins (16‐bit system). Direct memory access – this feature has been built into modern computers and is a part of technological innovation and progress. It involves the transfer of data to or from the main hard drive of a computer system, without involving the central processing unit (CPU) in the procedure. Hardware subsystems found inside the computer are responsible for this action where the main system memory is accessed for some task. The CPU is not kept occupied; hence, it performs other functions at an efficient and faster rate. Directory – it is the storage unit for all the files in a computer system and also aids in the search process when you are looking for a particular file on the disk. All files and folders are arranged in an order that you prefer; such as according to date of modification, alphabetical order, size of file, etc. Disk – hardware inside the computer that stores data. Information is mapped on to the disk and can be accessed any time. It has a magnetic surface usually made of aluminum. The storage capacity of each drive is different. Disk controller – the electronic circuit inside a disk that enables communication between the drive and the central processing unit. Data is transferred via signals converted and transmitted by the disk controller. Disk drive controller – a circuit board on the front or back of a hard disk that acts like a liaison between the CPU and the disk drive. It enables the reading and writing of information or data on to the disk by the computer system. Disk operating system – DOS is a program or software that organizes and manages storage media on the computer system. The information or files inside the storage devices is organized and other processes are also controlled by this software.
Disk transfer rate – the speed at which information is transmitted to or away from a disk drive. The speed depends on the location of the track; data stored on the outer tracks of the disk is transferred at a faster rate as compared to that stored on the inner tracks. The rate is expressed in bits or bytes per second. Distribution channel – the intermediary party involved in the transfer of goods from one end to another. The process involves electronic transfer via electronic distributors. DMA – abbreviation for direct memory access (explained above). It is the fastest way of transferring data. DOS – disk operating system (explained above). Usually abbreviated as MS‐DOS. DRAM – it stands for dynamic random access memory. Acts as the main memory of the computer system. A number of capacitors get together to form a circuit and each bit of information or data is stored on a separate capacitor. Driver – a program that controls a device connected to a computer. It is dependent on hardware to perform its functions. The communication between the device and the computer takes place through the driver. Dolphin Data Lab http://www.dolphindatalab.com/