Glossary of Terms

Glossary

Archiving The process of storing data for long periods of time (decades) to provide regulatory compliance, data authenticity, media longevity, random access and low TCO.
Asynchronous replication Write is considered complete as soon as local storage acknowledges it. Remote storage is updated, but probably with a small lag. Performance is greatly increased, but in case of losing a local storage, the remote storage is not guaranteed to have the current copy of data and most recent data may be lost.
Backing up The process of making an additional copy of a data store for the purpose of restoring the state of that data store to within a day of a given point in time should the file be deleted or become corrupt.
RAID An acronym for Redundant Array of Independent Disks (sometimes incorrectly referred to as Redundant Array of Inexpensive Disks), is a technology that provides increased storage functions and reliability through redundancy. This is achieved by combining multiple disk drive components into a logical unit, where data is distributed across the drives in one of several ways called 'RAID levels'.
Replication Is the process of sharing information so as to ensure consistency between redundant resources.This redundancy protects the users against failure of one of the devices but not the deletion or corruption of a file as this new state will be rapidly replicated.
Revision control A system that automatically stores previous revisions of a file after each 'commit'. This provides a finer level of granularity than traditional backups with regards to restoring previous versions of a file.
If a file is overwritten several times during the day it is possible to revert to any previous version of the file. Depending on the file type, revision control can also allow several people to edit a file simultaneously and then merge the various edits when they are committed to the server.
Synchronous replication Guarantees 'zero data loss' by the means of atomic write operation, i.e. write either completes on both sides or not at all. Write is not considered complete until acknowledgement by both local and remote storage.
Most applications wait for a write transaction to complete before proceeding with further work, hence overall performance decreases considerably. Inherently, performance drops proportionally to distance.