Network Hardware User Manual

U3585-J-Z125-8-76 449
Glossary
global storage (GS)
Global storage is a form of semiconductor-based expansion memory which has been
made non-volatile by a number of measures. It has an access granularity of 4K and can
be expanded up to 2x4 Gbyte depending on the system. As with expanded storage,
transfers between global storage and main memory are initiated using machine instruc-
tions. This means that an I/O request is processed synchronously if handled from the
cache. There is thus no change of task.
Global storage is not only used as a cache, but can also be used as a paging device as
required.
hardware service time (DCS)
See “service times definition (DCS, I/O operations)” on page 455.
hardware service time (non-DCS)
Time for which devices are busy with I/O operations, also called hardware duration. The
hardware duration is defined as the time between I/O initiation (SDV instruction) and
I/O termination (channel interrupt).
hiperfile concept
Hiperfiles (high-performance file) in BS2000 are a means of accelerating file
processing. This concept is based on the use of particularly fast storage media when
processing a file in order to avoid I/O bottlenecks and thus increase the performance of
the entire system.
These storage media are used to buffer data to be written to or read from disk. This
avoids the longer I/O times associated with disk accesses.
Extended memory (ES, GS) or disk controllers with integrated caches can be used as
storage media.
In this manual, hiperfiles are files with the attribute PERFORMANCE=*HIGH or *VERY-
HIGH.
initiation
After a task has been activated, the system must reach a decision on initiation. When it
is initiated, the task can use a CPU, i.e. compute.
input/output, logical level
On the logical level, the user uses macro calls (e.g. GET, PUT) to initiate system
functions which control data interchange with the peripheral devices, block and unblock
data, and handle any errors that may occur.