Data Backup Glossary (Letter A)
ABARS
Aggregate group backup and recovery support (ABARS) is a backup system for MVS S/390 mainframes from IBM. ABARS performs data backup and recovery processes on a predefined set of data called an aggregate. During backup processing, the data is packaged as a single entity in preparation for taking it offsite. This enables the recovery of individual applications in user-priority sequence. The original design of ABARS was for use in disaster recovery, but is also used for transfer of workloads and remote distribution of data.
Active-active
Also called dual active, active-active is a network of independent processing nodes in which each node has access to a replicated database. This database access enables each node to access and use a single application. In an active-active system, all requests are load balanced across all available processing capacity. When a failure occurs on a node, another node in the network takes its place.
Agent
A program that performs one or more services (such as gathering information from the Internet), acting for or as a principal. In an EVault solution, an agent is installed on each server or device needing data protection. It requires no changes to underlying server hardware. The agent installs directly onto multiple operating system environments with minimal overhead. Communicating closely with the other two modules—EVault Director and CentralControl—the agent initiates ongoing, delta (or block-level change) processing of backup data. It also works to perform adaptive compression for more compact data transmission over LANs or WANs. The agent also can encrypt data prior to the data being sent.
Appliance
An intelligent device programmed to perform a single well-defined function, such as providing backup, file, web, network, or print services. Appliances differ from general purpose computers in that their software is normally customized for the function they perform, pre-loaded by the vendor, and not alterable by the user.
Archive(n.)
A disk, tape, or directory that contains files that have been moved off primary storage.
A file that contains one or more files in a compressed format. Due to the file’s content or age, it is infrequently accessed and can be stored in slower, lower cost devices.
(v.) To move files to a long-term storage medium for backup.
(adj.) In DOS systems, the archive attribute marks files that have been modified since the last backup.
Asynchronous replication
A replication technique in which data must be committed to storage at only the primary site and not the secondary site before the write is acknowledged to the host. Data is then forwarded to the secondary site as the network capabilities permit.
ATA disk on chip
ATA disk on chip (ADC) is a chip that contains both a solid state disk (SSD) and an ATAPI bus interface. ADC is housed in a 600 mm 32-pin DIP package and uses a standard ATA/IDE protocol. ADC is most commonly used in thin client systems, PDAs, and other small form factor devices.
Automated cartridge system
An automated cartridge system (ACS) is a storage and retrieval system, often used for library management. The ACS provides cartridge storage cells, transports, and a robotic mechanism to move cartridges between the cells.
Automated cartridge system library software
Automated cartridge system library software (ACSLS) is the software that controls an automated cartridge system (ACS).
Automatic backup system
An automatic backup system triggers backups by event—for example, a schedule point or a threshold reached—rather than by human action.
Automatic failover
The automatic substitution of a functionally equivalent system component for a failed one. The term failover is most often applied to intelligent controllers connected to the same storage devices and host computers. If one of the controllers fails, failover occurs, and the survivor automatically takes over its I/O load.
Availability
In computer systems and networking, the amount of time that a system is available during those time periods when it is expected to be available, often measured as a percentage of an elapsed year.