Managing Superdome Complexes: A Guide for HP-UX System Administrators

Planning Superdome Configurations
Building Blocks and Definitions
Appendix A308
Memory Each cell can contain up to 16 GB RAM in 2 GB increments.
Performance and High Availability For high availability reasons, a cell
should contain at least 8 memory DIMMs (Dual Inline Memory Modules) for a
minimum of 4 GB RAM. For the best performance, all the cells in a partition
should contain the same amount of RAM. This is because all the memory in a
partition is fully cache-line-interleaved, meaning that each cell’s memory
forms part of a common pool used by processes running on that partition. If one
cell in the partition has more memory than the others, that cell will contribute
disproportionately to the pool and the connections to and from it will be
overworked, degrading performance.
See also “Choosing Cells for Partitions” on page 325.
Cell Compatibility
When a partition boots, PDC selects a core cell (see “Core Cell” on page
309). Other cells in the partition are allowed to boot if they match the
core cell in the following respects:
• The firmware revisions have the same major number.
• The cache sizes of the processors are the same, and the processors are
of the same type.
The Partition Manager (parmgr) will warn you if you try to configure an
incompatible cell into a partition.
Cell Connectivity
Cells communicate with each other (within a partition); and with I/O
devices by means of an I/O chassis (or, if the cell in question is not
connected to an I/O chassis, via a cell that is connected to I/O).
Cell I/O At least one cell in a partition must be connected to an I/O
chassis, and preferably more than one (see “Partitions, Cells and I/O
Chassis” on page 333).
A cell can be connected to no more than one I/O chassis, and an I/O
chassis can be connected to no more than one cell. Unless you add an I/O
expansion cabinet, this means that a maximum of four cells (out of a
possible eight in a CPU cabinet) can be directly connected to I/O. Adding
an I/O expansion cabinet would theoretically allow all eight cells in a full
CPU cabinet to be connected to I/O. Cells that have I/O are connected to
an I/O chassis via the System Bus Adapter, which in turn is connected
to the cards in the individual I/O slots, via Local Bus Adapter chips.
See “I/O Cards” on page 317 for more information.