Expand Configuration and Management Manual (G06.24+)

Expand Overview
Expand Configuration and Management Manual—523347-008
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Programmatic Access
Programmatic Access
When accessing a file or another resource programmatically across an Expand
network, you use the same procedure calls you would use when writing a local
application. With a few exceptions, applications that were written to run in a local
environment can be used virtually unchanged in a network environment.
Expand Subsystem and the NonStop Kernel
The Expand subsystem is an extension of the HP NonStop Kernel operating system.
You can use the same methods for remote and local file access because the NonStop
Kernel and the Expand subsystem provide a uniform, message-based interface
between applications and operating system processes on different servers. The
message-based interface has two parts: the file system and the message system.
The size of the message sent between Expand processes is determined by many
factors.
For G06.06 and D40 RVUs, the upper size limit of 32K bytes has been increased to
60K bytes, with the following limitations.
•
The 60K byte messages may only be sent between nodes which support 60K byte
messaging. The Expand line handlers at both the source and target nodes (CPUs)
must support the same size setting, that is, they must be at the same software
version (intermediate node versions do not matter).
•
Within any one node, Expand line handlers must all be at the same version.
•
All nodes supporting the 60K byte messages are required to use L4 Extended
packets: L4EXTPACKETS ON.
•
The NonStop Kernel file system limit of 56K bytes has not been increased.