NonStop S-Series Server Description Manual (G06.24+)

HP NonStop S-Series Server Description Manual—520331-003
10-1
10 Input/Output Operations
This section describes the operating sequences by which processors in NonStop
S-series servers transfer data to and from input/output devices. Before reading this
section, you should have read Section 2, Principles of System Operation, for a basic
understanding of ServerNet transactions and ServerNet packets. ServerNet
transactions (request and response) form the basis for all input and output operations
through the ServerNet fabrics.
Doing communications input/output is so fundamentally different from doing storage
input/output that the operations need to be described separately. The first three topics
in this section provide a comparison of similarities and differences, and the remainder
of the section separately discusses storage operations (next five topics) and then
communications operations (final five topics).
Topics in this section are:
Storage and Communications I/O Compared
Overview of the I/O System
Layers of I/O Components
I/O Process Models for Storage I/O
Storage Operation Queuing
Packaging and Delivery of Storage Commands
Storage Read Request Processing
Storage Write Request Processing
Communications Operation Queuing
Application of Communications Queues
Typical Use of Queue Pairs
Actions for Empty or Full Queues
Communications Request Processing