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.

Glossary 347