NonStop S-Series Planning and Configuration Guide (G06.25+)

HP NonStop S-Series Planning and Configuration Guide—523303-015
6-1
6
ServerNet Communication Pathways
This section describes the structure and operations of the communication pathways
provided by each PMF CRU, IOMF CRU or IOAM, and SEB in your NonStop S-series
system.
When CRU Removal Might Stop
Communications
If you remove a PMF CRU, IOMF CRU, or SEB from your NonStop S-series system,
your system can continue operating. Your system maintains two ServerNet fabrics, and
all processes simply switch to the other fabric.
However, after all processes have shifted to that other fabric, your system can
experience errors under these circumstances:
•
CRU removal: The CRU you removed might provide the only pathway along which
several components can communicate with the only remaining fabric. Thus, you
disconnect those components from the rest of the system.
•
Preexisting faults: If a fault then occurs on the second fabric, some components
will be affected.
Therefore, before you remove a PMF CRU, IOMF CRU, or SEB from any
enclosure, you must ensure that the rest of the system is fully functional.
Note. In this section, unless otherwise indicated:
•
Information about PMF CRUs also applies PMF 2 CRUs.
•
Information about IOMF CRUs also applies to IOMF 2 CRUs.
•
Information about SEBs also applies to MSEBs.
•
The IOAM enclosure appears to the NonStop S-series server as though it were another
I/O enclosure, and it is interchangeable with I/O enclosures attached to group 01 in
ServerNet communication pathways on S76000 and later NonStop S-series systems.
When CRU Removal Might Stop Communications 6-1
PMF CRUs and Communication Pathways 6-2
SEBs, MSEBs, and Communication Pathways 6-9
Communication Pathways in Different Topologies 6-15
Determining the Communication Pathways in Your System 6-18
Caution. If you remove more than one CRU at a time from anywhere in a system while the
system is online, results are unpredictable. Always complete the entire replacement procedure
for any CRU, including resuming operations, before beginning to replace another CRU. Any
exceptions to this rule will be stated in the replacement procedure.