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A stub file is a computer file that appears to the user to be on disk and immediately available for use, but is actually held either in part or entirely on a different storage medium. When a stub file is accessed, device driver software intercepts the access, retrieves the data from its actual location and writes it to the file, then allows the user's access to proceed. Typically, users are unaware that the file's data is stored on a different medium, though they may experience a slight delay when accessing such a file. [1]
File stubbing, the act of creating stub files, is a Hierarchical storage management (HSM) concept.
The usual purpose of stubbing files is to move data from an expensive high-speed storage device such as a computer's hard drive to lower cost storage such as a magnetic tape, or an electro-optical disk, while not requiring users to know how to use specialised storage software to retrieve the data. It also allows a system manager to enforce the use of low cost storage when users would prefer to store their files on the highest availability, and highest cost, media supplied. [2]
Stubbing is a feature of many commercial file backup and archiving packages and is available for Microsoft Windows, Novell NetWare, Linux and other operating systems.
Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers.
A computer file is a computer resource for recording data in a computer storage device, primarily identified by its file name. Just as words can be written to paper, so can data be written to a computer file. Files can be shared with and transferred between computers and mobile devices via removable media, networks, or the Internet.
A RAM drive is a block of random-access memory that a computer's software is treating as if the memory were a disk drive. It is sometimes referred to as a virtual RAM drive or software RAM drive to distinguish it from a hardware RAM drive that uses separate hardware containing RAM, which is a type of battery-backed solid-state drive.
A disk image, in computing, is a computer file containing the contents and structure of a disk volume or of an entire data storage device, such as a hard disk drive, tape drive, floppy disk, optical disc, or USB flash drive. A disk image is usually made by creating a sector-by-sector copy of the source medium, thereby perfectly replicating the structure and contents of a storage device independent of the file system. Depending on the disk image format, a disk image may span one or more computer files.
A live CD is a complete bootable computer installation including operating system which runs directly from a CD-ROM or similar storage device into a computer's memory, rather than loading from a hard disk drive. A live CD allows users to run an operating system for any purpose without installing it or making any changes to the computer's configuration. Live CDs can run on a computer without secondary storage, such as a hard disk drive, or with a corrupted hard disk drive or file system, allowing data recovery.
Network-attached storage (NAS) is a file-level computer data storage server connected to a computer network providing data access to a heterogeneous group of clients. NAS is specialized for serving files either by its hardware, software, or configuration. It is often manufactured as a computer appliance – a purpose-built specialized computer. NAS systems are networked appliances that contain one or more storage drives, often arranged into logical, redundant storage containers or RAID. Network-attached storage removes the responsibility of file serving from other servers on the network. They typically provide access to files using network file sharing protocols such as NFS, SMB, or AFP. From the mid-1990s, NAS devices began gaining popularity as a convenient method of sharing files among multiple computers. Potential benefits of dedicated network-attached storage, compared to general-purpose servers also serving files, include faster data access, easier administration, and simple configuration.
In computer storage, a tape library, sometimes called a tape silo, tape robot or tape jukebox, is a storage device that contains one or more tape drives, a number of slots to hold tape cartridges, a barcode reader to identify tape cartridges and an automated method for loading tapes. Additionally, the area where tapes that are NOT currently in a silo are stored is also called a tape library. Tape libraries can contain millions of tapes.
In computing, file system or filesystem is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one large body of data with no way to tell where one piece of data stopped and the next began, or where any piece of data was located when it was time to retrieve it. By separating the data into pieces and giving each piece a name, the data is easily isolated and identified. Taking its name from the way a paper-based data management system is named, each group of data is called a "file." The structure and logic rules used to manage the groups of data and their names is called a "file system."
A remote, online, or managed backup service, sometimes marketed as cloud backup or backup-as-a-service, is a service that provides users with a system for the backup, storage, and recovery of computer files. Online backup providers are companies that provide this type of service to end users. Such backup services are considered a form of cloud computing.
Hierarchical storage management (HSM) is a data storage technique that automatically moves data between high-cost and low-cost storage media. HSM systems exist because high-speed storage devices, such as solid state drive arrays, are more expensive than slower devices, such as hard disk drives, optical discs and magnetic tape drives. While it would be ideal to have all data available on high-speed devices all the time, this is prohibitively expensive for many organizations. Instead, HSM systems store the bulk of the enterprise's data on slower devices, and then copy data to faster disk drives when needed. In effect, HSM turns the fast disk drives into caches for the slower mass storage devices. The HSM system monitors the way data is used and makes best guesses as to which data can safely be moved to slower devices and which data should stay on the fast devices.
Write once read many (WORM) describes a data storage device in which information, once written, cannot be modified. This write protection affords the assurance that the data cannot be tampered with once it is written to the device.
In computing, data recovery is a process of salvaging 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).
IBM Spectrum Protect is a data protection platform that gives enterprises a single point of control and administration for backup and recovery. It is the flagship product in the IBM Spectrum Protect family.
In computer science, storage virtualization is "the process of presenting a logical view of the physical storage resources to" a host computer system, "treating all storage media in the enterprise as a single pool of storage."
Mounting is a process by which the operating system makes files and directories on a storage device available for users to access via the computer's file system.
Disk encryption is a technology which protects information by converting it into unreadable code that cannot be deciphered easily by unauthorized people. Disk encryption uses disk encryption software or hardware to encrypt every bit of data that goes on a disk or disk volume. It is used to prevent unauthorized access to data storage.
StorNext File System (SNFS), colloquially referred to as "StorNext" is a shared disk file system made by Quantum Corporation. StorNext enables multiple Windows, Linux and Apple workstations to access shared block storage over a Fibre Channel network. With the StorNext file system installed, these computers can read and write to the same storage volume at the same time enabling what is known as a "file-locking SAN." StorNext is used in environments where large files must be shared, and accessed simultaneously by users without network delays, or where a file must be available for access by multiple readers starting at different times. Common use cases include multiple video editor environments in feature film, television and general video post production.
Secure USB flash drives protect the data stored on them from access by unauthorized users. USB flash drive products have been on the market since 2000, and their use is increasing exponentially. As both consumers and businesses have increased demand for these drives, manufacturers are producing faster devices with greater data storage capacities.
A storage area network (SAN) or storage network is a computer network which provides access to consolidated, block-level data storage. SANs are primarily used to access data storage devices, such as disk arrays and tape libraries from servers so that the devices appear to the operating system as direct-attached storage. A SAN typically is a dedicated network of storage devices not accessible through the local area network (LAN).
The Active Archive Alliance is a trade association that promotes a method of tiered storage. This method provides users access to data across a virtual file system that migrates data between multiple storage systems and media types including solid-state drive/flash, hard disk drives, magnetic tape, optical disk, and cloud. The result of an active archive implementation is that data can be stored on the most appropriate media type for the given retention and restoration requirements of that data. This allows less time sensitive or infrequently accessed data to be stored on less expensive media and eliminates the need for an administrator to manually migrate data between storage systems. Additionally, since storage systems such as tape libraries have low power consumption, the operational expense of storing data in an active archive is significantly reduced.