NonStop S-Series Planning and Configuration Guide (G06.29+)

Topologies
HP NonStop S-Series Planning and Configuration Guide—523303-021
3-15
The ServerNet Topology Configuration Value and
CRU Replacement
The ServerNet Topology Configuration Value and CRU
Replacement
When power is first applied to a PMF CRU, IOMF CRU, SEB, or MSEB, its ServerNet
router is initialized. This can occur when the entire enclosure is first powered on or
when one of these CRUs is inserted into a powered enclosure, such as during online
CRU replacement.
If you insert a PMF CRU or IOMF CRU into an enclosure that is already initialized
(powered on), the newly inserted CRU is initialized.
During a successful online CRU replacement, the ServerNet topology configuration
value of the replacement CRU is overwritten by the value from the other PMF CRU or
IOMF CRU in that enclosure.
If you do not follow proper PMF CRU or IOMF CRU replacement procedures, then
when you insert the CRU into the enclosure, the configuration data might not be
synchronized with the rest of the enclosure, which could leave the incorrect ServerNet
topology configuration value stored on the newly inserted CRU. The next time that
CRU is initialized, it might use the wrong ServerNet topology configuration value.
ServerNet Routing Tables
Processor enclosures in the inner tetrahedron (groups 01, 02, 03, 04) contain
ServerNet routing tables that are critical. If these enclosures have incorrect ServerNet
routing tables, your system does not operate correctly. For example, if group 03
contains the wrong ServerNet topology configuration value, your system cannot access
any enclosures attached to that enclosure.
The ServerNet routing tables in processor enclosures in the outer tetrahedron (groups
05, 06, 07, and 08) have no effect on how your system operates. These enclosures are
always automatically configured with a running ServerNet topology configuration value
of Tetra 16. However, the stored ServerNet topology configuration value in these
enclosures could be set to Tetra 8, which would remain Tetra 8 even after a system
power cycle. This mismatch between the stored and running values is potentially
confusing to system personnel. To avoid confusion, make sure that all stored
ServerNet topology configuration values in the enclosures of the outer tetrahedron are
Tetra 16.
All ServerNet routing tables in I/O enclosures are identical, and they have no effect on
how your system operates. However, I/O enclosures can contain the wrong stored
ServerNet topology configuration values for your system, and this mismatch is
potentially confusing. To avoid confusion, correct any incorrect stored ServerNet
topology configuration values in the I/O enclosures.
You can change stored ServerNet topology configuration values online at any
convenient time. Changing the running ServerNet topology configuration values
requires a system power-cycle.
Note. Resetting an SP does not reconfigure ServerNet routing tables.