Global Mirror is an IBM

IBM

International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

 technology that provides data replication over extended distances between two sites 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,...

 and disaster recovery

Disaster recovery

Disaster recovery is the process, policies and procedures related to preparing for recovery or continuation of technology infrastructure critical to an organization after a natural or human-induced disaster. Disaster recovery is a subset of business continuity...

. If adequate bandwidth

Bandwidth (computing)

In computer networking and computer science, bandwidth, network bandwidth, data bandwidth, or digital bandwidth is a measure of available or consumed data communication resources expressed in bits/second or multiples of it .Note that in textbooks on wireless communications, modem data transmission,...

 exists, Global Mirror provides an recovery point objective

Recovery point objective

-Recovery point objective :When computers used for normal "production" business services are affected by a "Major Incident" that cannot be fixed quickly, then the Information Technology Service Continuity Plan is performed, by the ITSC recovery team...

 (RPO) of as low as 3-5 seconds between the two sites at extended distances with no performance impact on the application at the primary site. It replicates the data asynchronously and also forms a consistency group at a regular interval allowing a clean recovery of the application.

The two sites can be on separate continents or simply on different utility grids

Grid computing

Grid computing is a term referring to the combination of computer resources from multiple administrative domains to reach a common goal. The grid can be thought of as a distributed system with non-interactive workloads that involve a large number of files...

. IBM also provides a synchronous data replication called Metro Mirror, which is designed to support replication at "Metropolitan" distances of (normally) less than 300 km.

Global Mirror is based on existing IBM Copy Services functions: Global Copy and FlashCopy

FlashCopy

FlashCopy is an IBM feature supported on various IBM storage devices that makes it possible to create, nearly instantaneously, Point in Time copies of entire logical volumes or data sets. The Hitachi Data Systems implementation providing similar function is branded as ShadowImage...

. Global Mirror periodically invokes a point-in-time copy at the primary site, at regular intervals, without impacting the I/O to the source volumes. Then it transfers the copy to the recovery site. By grouping many volumes into one Global Mirror session multiple volumes may be copied to the recovery site simultaneously while maintaining point-in-time consistency across those volumes.

Global Mirror can be combined with a wide area clustering product like Geographically Dispersed Parallel Sysplex (GDPS), HACMP/XD, or CAW to provide for automated failover between sites. This combined solution provides lower recovery time objective

Recovery Time Objective

The recovery time objective is the duration of time and a service level within which a business process must be restored after a disaster in order to avoid unacceptable consequences associated with a break in business continuity....

 (RTO), because it allows most applications to automatically resume productive operation in 30-600 seconds.

The Global Mirror function is available on IBM's enterprise storage devices including the DS8100, the DS8300, the DS6800, the Enterprise Storage Server

IBM Enterprise Storage Server

The IBM Enterprise Storage Server or the Shark is an enterprise storage array from IBM.-History:Originally, in 1998 IBM released the IBM 2105 Versatile Storage Server...

 Models 800 and 750, midrange storage servers DS4000 family and the IBM SAN Volume Controller

IBM SAN Volume Controller

In computer data storage, the IBM SAN Volume Controller is a block storage virtualization appliance that belongs to the IBM System Storage product family. SVC implements an indirection, or "virtualization", layer in a Fibre Channel storage area network .- Architecture :SVC is always deployed as a...

.