Posts Tagged ‘glossary’

Data Backup Glossary (Letter S)

November 11th, 2011 Comments off

SaaS: Software as a Service
Software as a Service (SaaS) is a software delivery method that provides access to software and its functions remotely as a web-based service. Software as a Service allows organizations to access business functionality at a cost typically less than paying for licensed applications since SaaS pricing is based on a monthly fee. Also, because the software is hosted remotely, users don’t need to invest in additional hardware. Software as a Service removes the need for organizations to handle the installation, setup, and often daily upkeep and maintenance. Software as a Service may also be referred to as simply hosted applications.

SaaS: Storage as a Service
Storage as a Service (SaaS) is a storage model in which a business or organization (the client) rents or leases storage space from a third-party provider. Data is transferred from the client to the service provider via the Internet and the client then accesses the stored data using software provided by the storage provider. The software is used to perform common tasks related to storage, such as data backups and data transfers. Storage as a Service is popular with SMBs because there usually are no start-up costs (for example, servers, hard disks, IT staff, and so on) involved. Businesses pay for the service based only on the amount of storage space used. Storage as a Service may also be called hosted storage.

A Storage Area Network (SAN) is a high-speed subnetwork of shared storage devices. A storage device is a machine that contains nothing but a disk or disks for storing data. A SAN’s architecture works in a way that makes all storage devices available to all servers on a LAN or WAN. As more storage devices are added to a SAN, they too will be accessible from any server in the larger network. In this case, the server merely acts as a pathway between the end user and the stored data. Because stored data does not reside directly on any of a network’s servers, server power is utilized for business applications, and network capacity is released to the end user.

SAN fabric
The hardware that connects workstations and servers to storage devices in a SAN. The SAN fabric enables any-server-to-any-storage device connectivity through the use of Fibre Channel switching technology.

SAN services
A technology used by businesses to obtain greater flexibility in their data storage. A Storage Area Network (SAN) provides raw storage devices across a network, and is typically sold as a service to customers who also purchase other services. SAN services may also be administered over an existing, local fiber network, and administered through a service subscription plan.

Scratch disk
Space dedicated on a hard drive for temporary storage of data. Scratch disks are commonly used in graphic design programs, such as Adobe Photoshop. Scratch disk space is only for temporary storage and cannot be used for permanently backing up files. Scratch disks can be set to erase all data at regular intervals so that the disk space is left free for future use. The management of scratch disk space is typically dynamic, occurring when needed.

The first full backup of company data.

Secret storage technology
A technology for encrypting and hiding data on a hard drive, flash drive, or when transferring files. Secret storage is a portion of encrypted data, hidden in some file or FAT/FAT32/NTFS partitions. To the end-user, it looks like a folder in which he may add files and folders and protect it with a password.

Selective backup
A type of backup where only the user-specified files and directories are backed up. A selective backup is commonly used for backing up files which change frequently or in situations where the space available to store backups is limited. Also called a partial backup.

Serial storage architecture
Serial storage architecture (SSA) is an open industry-standard interface that provides a high-performance, serial interconnect technology used to connect disk devices and host adapters. SSA serializes the SCSI data set and uses loop architecture that requires only two wires: transmit and receive. The SSA interface also supports full-duplex, so it can transmit and receive data simultaneously at full speed.

Server cage area
The area where a company stores its data center equipment. This area is protected from personnel access.

Service-level agreement
A service-level agreement (SLA) is an agreement between a service provider, such as an IT department, an Internet services provider, or an intelligent device acting as a server, and a service consumer. A service level agreement defines parameters for measuring the service, and states quantitative values for those parameters.

Slack space
The unused space in a disk cluster. The DOS and Windows file systems use fixed-size clusters. Even if the actual data being stored requires less storage than the cluster size, an entire cluster is reserved for the file. The unused space is called the slack space. DOS and older Windows systems use a 16-bit file allocation table (FAT), which results in very large cluster sizes for large partitions. For example, if the partition size is 2 GB, each cluster will be 32 K. Even if a file requires only 4 K, the entire 32 K will be allocated, resulting in 28 K of slack space. Windows 95 OSR 2 and Windows 98 resolve this problem by using a 32-bit FAT (FAT32) that supports cluster sizes smaller than 1K.

Small and medium enterprise (SME)
Companies whose headcount or turnover fall below certain limits. In the United states, a small business is often defined as having fewer than 100 employees. A medium-size business is often defined as having fewer than 500 employees.

Small to mid-size business (SMB)
Companies whose headcount or turnover fall below certain limits. In the United states, a small business is often defined as having fewer than 100 employees. A mid-size business is often defined as having fewer than 500 employees.

Snapshot backup
A virtual copy of a device or file system. Snapshots imitate the way a file or device looked at the precise time the snapshot was taken. It is not a copy of the data, only a picture in time of how the data was organized. Snapshots can be taken according to a scheduled time and provide a consistent view of a file system or device for a backup and recovery program to work from.

Solid state disk
A solid state disk (SSD) is a high-performance plug-and-play storage device that contains no moving parts. SSD components include either DRAM or EEPROM memory boards, a memory bus board, a CPU, and a battery card. Because SSDs contain their own CPUs to manage data storage, they are a lot faster (18MBps for SCSI-II and 35 MBps for UltraWide SCSI interfaces) than conventional rotating hard disks; therefore, they produce highest possible I/O rates.

Spin valve
Another name for a giant magnetoresistive(GMR) head. The term was coined by IBM.


  • The capacity of a device to hold and retain data.
  • Short for mass storage.

Storage bay bridge
Storage bridge bay (SBB) is a specification that defines mechanical, electrical, and low-level enclosure management requirements for an enclosure controller slot that will support a variety of storage controllers from a variety of independent hardware vendors and system vendors. Any storage controller design based on the SBB specification will be able to fit, connect, and operate within any storage enclosure controller slot design based on the same specification.

Storage Consolidation
The concept of centralized storage where resources are shared among multiple applications and users. Traditionally, organizations have deployed servers with direct-attached storage (DAS) as file servers. However, many organizations are facilitating server consolidation by deploying network-attached storage (NAS). NAS provides a single purpose device that can provide CIFS and NF- connected storage that can scale from gigabyte to petabytes.

Storage device
A device capable of storing data. The term usually refers to mass storage devices, such as disk and tape drives.

Storage footprint
The amount of energy, physical space, and other equipment necessary to run a data storage management system.

Storage management
The tools, processes, and policies used to manage storage networks and storage services such as virtualization, replication, mirroring, security, compression, traffic analysis, and other services. The phrase also encompasses other storage technologies, such as process automation, storage management and real-time infrastructure products, and storage provisioning. In some cases, the phrase storage management may be used in direct reference to storage resource management (SRM).

Storage management initiative specification
Storage management initiative specification (SMI-S) is an interface standard that enables interoperability in both hardware and software between storage products from different vendors used in a SAN environment. The interface provides common protocols and data models that storage product vendors can use to ensure end user manageability of the SAN environment.

Based on the CIM and Web-Based Enterprise Management (WBEM) standards, SMI-S adds common interoperable and extensible management transport, automated discovery, and resource locking functions. SMI-S was developed by the Storage Networking Industry Association (SNIA) in 2002.

Storage networking
A high-speed network of shared storage devices. The storage network is used by IT departments to connect different types of storage devices with data servers for a larger network of users. As more storage devices are added to the storage network, they too will be accessible from any server in the larger network.  Storage networking is a phrase most commonly associated with enterprises and data centers.

Storage optimization
The implementation and management of tiered storage solutions to obtain a lower cost per capacity across a corporation or enterprise. Storage optimization is an information lifecycle management (ILM) strategy.

Storage over IP
Storage over IP (SoIP) technology refers to the merging of Fibre Channel technologies with IP-based technology to allow for accessing storage devices over TCP/IP networks. SoIP is the framework for storage area networking (SAN) using Internet Protocol (IP) networks to directly connect servers and storage. SoIP products are designed to support transparent interoperability of storage devices based on Fibre Channel, SCSI, and a new class of Gigabit Ethernet storage devices using iSCSI and iFCP. Existing Fibre Channel or SCSI devices, such as servers with host bus adapters (HBAs) or storage subsystems, can be included in an SoIP storage network without modification.

Storage resource management
Storage resource management (SRM) refers to software that manages storage from a capacity, utilization, policy, and event management perspective. SRM includes bill-back, monitoring, reporting, and analytic capabilities that allow you to drill down for performance and availability.
Key elements of SRM include asset management, charge back, capacity management, configuration management, data and media migration, event management, performance and availability management, policy management, quota management, and media management.

Storage service provider
A storage service provider (SSP) is a company that provides computer storage space and related management services. SSPs also offer periodic backup, archiving, and the ability to consolidate data from multiple company locations so that data can be effectively shared.

Storage virtualization
Storage virtualization is the amalgamation of multiple network storage devices into what appears to be a single storage unit. Storage virtualization is often used in a SAN (storage area network), a high-speed subnetwork of shared storage devices, and makes tasks such as archiving, backup, and recovery easier and faster. Storage virtualization is usually implemented via software applications.

To copy data from a CPU to memory, or from memory to a mass storage device.

The process of distributing data across several storage devices to improve performance.

In magnetic disk drive storage technology, the fluctuation of magnetization due to thermal agitation. When the areal density—the number of bits that can be stored on a square inch of disk media—of a disk medium reaches 150 gigabits per square inch, the magnetic energy holding the bits in place on the medium becomes equal to the ambient thermal energy within the disk drive itself. When this happens, the bits are no longer held in a reliable state and can “flip,” scrambling the data that was previously recorded. Because of superparamagnetism, hard drive technologies are expected to stop growing once they reach a density of 150 gigabits per square inch.

In Fibre Channel, a receiver’s identification of a transmission word boundary.

Synthetic backup
A synthetic backup is identical to a regular full backup in terms of data, but it is created when data is collected from a previous, older full backup and assembled with subsequent incremental backups. The incremental backup will consist only of changed information. A synthetic backup is used when time or system requirements do not allow for a full complete backup. The end result of combining a recent full backup archive with incremental backup data is two kinds of files which are merged by a backup application to create the synthetic backup. Benefits to using a synthetic backup include a smaller amount of time needed to perform a backup, and lower system restore times and costs. This backup procedure is called “synthetic” because it is not a backup created from original data.

Categories: Data Backup Tags: , ,

Data Backup Glossary (Letter Q)

October 26th, 2011 Comments off

Data Backup Glossary (Letter Q)RAID
See redundant array of independent (or inexpensive) disks.

See redundant array of independent nodes.

Raised floor
A type of flooring supported by a metal grid and typically used in data centers. Raised flooring can be removed in pieces to allow for cabling, wiring, and cooling systems to run under the floor space. When the floor is raised, it usually can accommodate space for walking or crawling in.

The recreation of a past operational state of an entire application or computing environment. Recovery is required after an application or computing environment has been destroyed or otherwise rendered unusable. It may include restoration of application data, if that data has been destroyed as well.

Recovery point objective
Recovery point objective (RPO) is the maximum acceptable time period prior to a failure or disaster during which changes to data may be lost as a consequence of recovery. Data changes preceding the failure or disaster by at least this time period are preserved by recovery. Zero is a valid value and is equivalent to a “zero data loss” requirement.

Recovery time objective
Recovery time objective (RTO) is the period of time after an outage in which the systems and data must be restored to the predetermined recovery point.

Red Hat Global File System
Red Hat Global File System (GFS) is an open source cluster file system and volume manager that executes on Red Hat Enterprise Linux servers attached to a storage area network (SAN). It enables a cluster of Linux servers to share data in a common pool of storage to provide a consistent file system image across server nodes. Red Hat Global File System works on all major server and storage platforms supported by Red Hat.

The inclusion of extra components of a given type in a system (beyond those required by the system to carry out its function) for the purpose of enabling continued operation in the event of a component failure.

Redundant array of independent (or inexpensive) disks
Redundant array of independent (or inexpensive) disks (RAID) is a category of disk drives that employ two or more drives in combination for fault tolerance and performance. RAID disk drives are used frequently on servers but aren’t generally necessary for personal computers. RAID allows you to store the same data redundantly (in multiple places) in a balanced way to improve overall performance.

Redundant array of independent nodes
Redundant array of independent nodes (RAIN) is a data storage and protection system architecture. It uses an open architecture that combines standard computing and networking hardware with management software to create a system that is more distributed and scalable. RAIN is based on the idea of linking RAID nodes together into a larger storage mechanism. In a RAIN setup, there are multiple servers, each with disk drive and RAID functionality, all working together as a RAIN, or a parity or mirrored implementation. RAIN may also be called storage grid.

Remote offices/branch offices (ROBOs)
Refers to corporate offices externally connected to a WAN or a LAN. These offices will often have one or more servers to provide branch users with file, print, and the other services required to maintain the daily routine.

(n.)  A copy of a collection of data.
(v.) The action of making a replicate as defined above.

To bring a desired data set back from the backup media.

Rotational latency
Also called rotational delay, the amount of time it takes for the desired sector of a disk (for example, the sector from which data is to be read or written) to rotate under the read-write heads of the disk drive. The average rotational latency for a disk is half the amount of time it takes for the disk to make one revolution. The term typically is applied to rotating storage devices, such as hard disk drives and floppy drives (and even older magnetic drum systems), but not to tape drives.

See recovery point objective.

See recovery time objective.

Run length limited
Run length limited (RLL) is an encoding scheme used to store data on newer PC hard disks. RLL produces fast data access times and increases a disk’s storage capacity over the older encoding scheme called MFM (modified frequency modulation).

Data Backup Glossary (Letter P)

October 10th, 2011 Comments off

Physical erase unit
A physical erase unit is the smallest memory area of the flash memory media that can be erased in a single erase operation. Its size varies between flash devices.

A physical entity that contains nodes. Platforms include all end devices that are attached to a Fabric, for example, hosts and storage subsystems. Platforms communicate with other platforms in the storage area network using the facilities of a Fabric or other topology

Portable image storage device
A small, portable storage device used for storing and viewing your digital images. The device is a portable hard drive in an enclosure that resembles handheld game consoles. The device usually offers USB and memory card readers as options for transferring your images directly to the device, as well as an LCD display for viewing the stored images. The device  may also have different controls for maneuvering through the images, such as forward, random, skip, and so on.

Primary storage
A somewhat dated term for main memory. Mass storage devices, such as disk drives and tapes, are sometimes called secondary storage.

A set of rules that control an interaction between two or more entities in communication with one another, for example,  TCP ports, Fibre Channel FC-4 processes, and polite humans.

Categories: Data Backup Tags: ,

Data Backup Glossary (Letter O)

September 17th, 2011 Comments off

Object-based storage device
Data Backup Glossary (Letter O)An object-based storage device (OSD) is a device that implements the standard in which data is organized and accessed as objects, where object means an ordered set of bytes (within the OSD) that is associated with a unique identifier. Objects are allocated and placed on the media by the OSD logical unit. With an OSD interface, metadata is associated directly with each data object and can be carried between layers and across storage device files. Records are no longer abstractions, but actual storage objects that are understood, managed, and secured at the device level.

Offline storage
Any storage medium that must be inserted into a storage drive by a person before it can be accessed by the computer system is considered to be a type of offline storage. Also called removable storage.

Online data storage
Also called Internet storage or hosted storage, online data storage is a data storage management solution that enables individuals or organizations to store their data on the Internet using a service provider, rather than storing the data locally on a physical disk, such as a hard drive or tape backup.

Open document management API
Open document management API (ODMA) is an open industry standard that enables desktop applications to interface with a document management system (DMS). ODMA simplifies cross-platform and cross-application file communication by standardizing access to document management through an API. ODMA allows multiple applications to access the same DMS without the need for a hard-coded link between the application and the DMS.

Operational data store
A type of database that serves as an interim area for a data warehouse in order to store time-sensitive operational data that can be accessed quickly and efficiently. In contrast to a data warehouse, which contains large amounts of static data, an operational data store contains small amounts of information that is updated through the course of business transactions. An operational data store will perform numerous quick and simple queries on small amounts of data, such as acquiring an account balance or finding the status of a customer order, whereas a data warehouse will perform complex queries on large amounts of data. An operational data store contains only current operational data while a data warehouse contains both current and historical data.

To record or copy new data over existing data, as in when a file or directory is updated. Data that is overwritten cannot be retrieved.
(n.) Refers to a file or directory that has been overwritten.

Categories: Data Backup Tags: , ,

Data Backup Glossary (Letter N)

August 29th, 2011 Comments off

Near-line storage
Data Backup Glossary (Letter N)Near-line storage is used by corporations, including data warehouses, as an inexpensive, scalable way to store large volumes of data. Near-line storage devices include DAT and DLT tapes (sequential access); optical storage such as CD-ROM, DVD, and Blu-ray; magneto-optical which utilize magnetic heads with an optical reader; and also slower P-ATA and SATA hard disk drives. Retrieval of data is slower than SCSI hard disk which is usually connected directly to servers or in a SAN environment. Near-Line implies that whatever media the information is stored on, it can be accessed via a tape library or some other method electronically as opposed to off-line which signified some human intervention is required, such as retrieving and mounting a tape. Near-line can be slower, but the type of data (historical archives, backup data, video, and others) dictates that the information will not require instant access and high throughput that SAN and SCSI can provide and is less expensive per byte.

Network-attached storage(NAS)
A network-attached storage (NAS) device is a server that is dedicated to nothing more than file sharing. NAS does not provide any of the activities that a server in a server-centric system typically provides, such as e-mail, authentication, or file management. NAS allows more hard disk storage space to be added to a network that already utilizes servers without shutting them down for maintenance and upgrades. With a NAS device, storage is not an integral part of the server. Instead, in this storage-centric design, the server still handles all of the processing of data but a NAS device delivers the data to the user. A NAS device does not need to be located within the server but can exist anywhere in a LAN and can be made up of multiple networked NAS devices.

Nyquist’s Law
Also called Nyquist’s Theorem. Before sound as acoustic energy can be manipulated on a computer, it must first be converted to electrical energy (using a transducer such as a microphone) and then transformed through an analog-to-digital converter into a digital representation. This is all accomplished by sampling the continuous input waveform a certain number of times per second. The more often a wave is sampled the more accurate the digital representation. Nyquist’s Law, named in 1933 after scientist Harry Nyquist, states that a sound must be sampled at least twice its highest analog frequency in order to extract all of the information from the bandwidth and accurately represent the original acoustic energy. Sampling at slightly more than twice the frequency will make up for imprecisions in filters and other components used for the conversion.

Categories: Data Backup Tags: , ,