IBM DS8000 Remote Mirror and Copy, Remote technical assistance information network Retain, Screen

redundant array of independent disks (RAID) A methodology of grouping disk drives for managing disk storage to insulate data from a failing disk drive.

refresh FlashCopy target volume

An option (previously called incremental FlashCopy) of the DS8000 that creates a point-in-time data copy without copying an entire volume for each point-in-time copy.

Remote Mirror and Copy

A feature of a storage server that constantly updates a secondary copy of a logical volume to match changes made to a primary logical volume. The primary and secondary volumes can be on the same storage server or on separate storage servers. See also Global Mirror, Metro Mirror and Global Copy.

remote technical assistance information network (RETAIN)

The initial service tracking system for IBM service support, which captures heartbeat and call-home records. See also support catcher and support catcher telephone number.

REQ/ACK

See request for acknowledgment and acknowledgment.

request for acknowledgment and acknowledgment (REQ/ACK)

A cycle of communication between two data transport devices for the purpose of verifying the connection, which starts with a request for acknowledgment from one of the devices and ends with an acknowledgment from the second device. The REQ and ACK signals help to provide uniform timing to support synchronous data transfer between an initiator and a target. The objective of a synchronous data transfer method is to minimize the effect of device and cable delays.

reserved allegiance

For zSeries, a relationship that is created in a control unit between a device and a channel path, or path group, when the device completes a Sense Reserve command. The allegiance causes the control unit to guarantee access (that is, busy status is not presented) to the device. Access is over the set of channel paths that are associated with the

allegiance; access is for one or more channel programs until the allegiance ends.

RETAIN

See remote technical assistance information network.

S

S/390 IBM enterprise servers based on Enterprise Systems Architecture/390 (ESA/390). S/390 is the currently accepted shortened form of the original name System/390.

S/390 storage

Storage arrays and logical volumes that are defined as connected to S/390 servers. This term is synonymous with count-key-data storage.

SAID See system adapter identification number. SAM See sequential access method.

SAN See storage area network.

SBCON

See Single-Byte Command Code Sets Connection.

screen

The physical surface of a display device upon which information is shown to users.

SCSI See small computer system interface.

SCSI device

A disk drive connected to a host through an I/O interface using the SCSI protocol. A SCSI device is either an initiator or a target. See also initiator and small computer system interface.

SCSI-FCP

Synonym for fibre-channel protocol, a protocol used to transport data between an open-systems host and a fibre-channel adapter on an DS8000. See also fibre-channel protocol and small computer system interface.

SCSI host systems

Host systems that are attached to the DS8000 with a SCSI interface. Such host systems run on UNIX, i5/OS, Windows NT, Windows 2000, or Novell NetWare operating systems.

SCSI ID

A unique identifier assigned to a SCSI

346IBM TotalStorage DS8000: Messages Reference