Extended Remote Copy or XRC 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...

 zSeries

ZSeries

IBM System z, or earlier IBM eServer zSeries, is a brand name designated by IBM to all its mainframe computers.In 2000, IBM rebranded the existing System/390 to IBM eServer zSeries with the e depicted in IBM's red trademarked symbol, but because no specific machine names were changed for...

 and System z9

System z9

IBM System z9 is a line of IBM mainframe. It was announced on July 25, 2005 and the first models were available on September 16, 2005. The System z9 also marks the end of the previously used eServer zSeries naming convention, and it is the last z/Architecture 1 machine.- Background :System z9 is a...

 mainframe computer

Mainframe computer

Mainframes are powerful computers used primarily by corporate and governmental organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning, and financial transaction processing.The term originally referred to the...

 technology for data replication. It combines supported hardware and z/OS

Z/OS

z/OS is a 64-bit operating system for mainframe computers, produced by IBM. It derives from and is the successor to OS/390, which in turn followed a string of MVS versions.Starting with earliest:*OS/VS2 Release 2 through Release 3.8...

 software to provide asynchronous replication over long distances. It is complementary to IBM's Peer to Peer Remote Copy

Peer to Peer Remote Copy

Peer to Peer Remote Copy or PPRC is a protocol to replicate a storage volume to another control unit in a remote site. Synchronous PPRC causes each write to the primary volume to be performed to the secondary as well, and the I/O is only considered complete when update to both primary and secondary...

 (PPRC) service, which is designed to operate either synchronously or asynchronously over shorter distances.

XRC as a z/OS copy services solution can be compared to Global Mirror

Global Mirror

Global Mirror is an IBM technology that provides data replication over extended distances between two sites for business continuity and disaster recovery. If adequate bandwidth exists, Global Mirror provides an recovery point objective of as low as 3-5 seconds between the two sites at extended...

 for ESS, which is a controller-based solution for either the open systems or z/Series environments. Both Global Mirror for ESS (Asynchronous PPRC) and XRC (Global Mirror for z/Series) are asynchronous replication technologies, although their implementations are somewhat different.

Extended Remote Copy or XRC is now known as Global Mirror for z/Series (XRC).

XRC is a z/Series asynchronous disk mirroring technique which is effective over any distance. It keeps the data time consistent across multiple ESS (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...

 or HDS (Hitachi Data Systems) disk subsystems at the recovery site.

XRC functions as a combination of disk (IBM ESS or HDS licensed) Microcode and application code running on a z/Series host and provides a recovery point that is time consistent across multiple disk subsystems.

The host component of the software is called the System Data Mover or SDM. The SDM ensures that no dependent writes are made out of sequence and data residing on the secondary volumes will always provide a time consistent copy of the primary volumes being mirrored.