IBM DS8000 Secondary control unit, Self-timed interface STI, Sequential access, Serial connection

device that is used in protocols on the SCSI interface to identify or select the device. The number of data bits on the SCSI bus determines the number of available SCSI IDs. A wide interface has 16 bits, with 16 possible IDs.

SDD See IBM Subsystem Multipathing Device Driver.

secondary control unit

The DS8000 to which a Remote Mirror and Copy secondary device is physically attached.

self-timed interface (STI)

An interface that has one or more conductors that transmit information serially between two interconnected units without requiring any clock signals to recover the data. The interface performs clock recovery independently on each serial data stream and uses information in the data stream to determine character boundaries and inter-conductor synchronization.

sequential access

A mode of accessing data on a medium in a manner that requires the storage device to access consecutive storage locations on the medium.

sequential access method (SAM)

An access method for storing, deleting, or retrieving data in a continuous sequence based on the logical order of the records in the file.

serial connection

A method of device interconnection for determining interrupt priority by connecting the interrupt sources serially.

server A host that provides certain services to other hosts that are referred to as clients.

A functional unit that provides services to one or more clients over a network. (GC)

service boundary

A category that identifies a group of components that are unavailable for use when one of the components of the group is being serviced. Service boundaries are provided on the DS8000, for example, in each host bay and in each cluster.

service clearance

The area that is required to open the service covers and to pull out components for servicing.

service information message (SIM)

A message sent by a storage server to service personnel through an zSeries operating system.

service personnel

A generalization referring to individuals or companies authorized to service the DS8000. The terms service provider, service representative, and IBM service support representative (SSR) refer to types of service personnel. See also service support representative.

service processor

A dedicated processing unit that is used to service a storage unit.

service support representative (SSR) Individuals or a company authorized to service the DS8000. This term also refers to a service provider, a service representative, or an IBM service support representative (SSR). An IBM SSR installs the DS8000.

SES SCSI Enclosure Services.

session

A collection of volumes within a logical subsystem that are managed together during the creation of consistent copies of data. All volumes in a session must transfer their data successfully to the remote site before the increment can be called complete.

SFP Small form factor pluggables.

shared storage

Storage that is configured so that multiple hosts can concurrently access the storage. The storage has a uniform appearance to all hosts. The host programs that access the storage must have a common model for the information on a storage device. The programs must be designed to handle the effects of concurrent access.

shortwave laser adapter

A connector that is used between host and DS8000 to support shortwave fibre-channel communication.

SIM See service information message.

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