In disk array

Disk array

A disk array is a disk storage system which contains multiple disk drives. It is differentiated from a disk enclosure, in that an array has cache memory and advanced functionality, like RAID and virtualization.Components of a typical disk array include:...

s, a business continuance volume, or BCV, is EMC Corporation

EMC Corporation

EMC Corporation , a Financial Times Global 500, Fortune 500 and S&P 500 company, develops, delivers and supports information infrastructure and virtual infrastructure hardware, software, and services. EMC is headquartered in Hopkinton, Massachusetts, USA.Former Intel executive Richard Egan and his...

's term for an independently addressable copy of data volume, that uses advanced mirroring technique for business continuity

Business continuity

Business continuity is the activity performed by an organization to ensure that critical business functions will be available to customers, suppliers, regulators, and other entities that must have access to those functions. These activities include many daily chores such as project management,...

 purposes.

BCVs can be detached from the active data storage at a point in time and mounted on non-critical servers to facilitate offline backup

Backup

In information technology, a backup or the process of backing up is making copies of data which may be used to restore the original after a data loss event. The verb form is back up in two words, whereas the noun is backup....

 or parallel processing

Parallel processing

Parallel processing is the ability to carry out multiple operations or tasks simultaneously. The term is used in the contexts of both human cognition, particularly in the ability of the brain to simultaneously process incoming stimuli, and in parallel computing by machines.-Parallel processing by...

. Once offline processes are completed, these BCVs can be either:

• discarded
• re-attached (re-synchronized) to the production data again
• used as a source to recover the production data

There are two types of BCVs:

• A clone BCV is a traditional method, and uses one-to-one separate physical storage (splitable disk mirror)
  • least impact on production performance
  • high cost of the additional storage
  • persistent usage

• A snapshot
  Snapshot (computer storage)
  In computer systems, a snapshot is the state of a system at a particular point in time. The term was coined as an analogy to that in photography. It can refer to an actual copy of the state of a system or to a capability provided by certain systems....
  
   BCV, that uses copy on write algorithm on the production volume
  • uses only a small additional storage, that only holds the changes made to the production volume
    • lower cost of the additional storage
    • reads and writes impact performance of production storage
  • once snapshot storage fills up, the snapshot becomes invalid and unusable
  • short-term usage