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

Planning Superdome Configurations
Rules and Guidelines for Configuring a Complex
Appendix A 331
Distributing Resources
• Each partition should consist of at least two cells.
• Each partition should contain at least two viable core cells.
See “Partitions, Cells and I/O Chassis” on page 333 for more
information.
• Each cell should have at least two active CPUs.
• Configure cells into partitions by powers of two if possible.
Because of the way memory interleaving is implemented (that is,
memory sharing among cells) you will get the best memory
performance from partitions comprising two, four, eight or sixteen
cells. (Single-cell partitions also provide good memory performance,
but are not recommended for other reasons.)
• Configure the same number of active processors and the same
amount of memory for each cell in a partition.
Partitions that conform to this guideline will perform better than
those that do not, because an uneven distribution of resources will
result in an uneven workload, overworking some connections and
underusing others.
• Each cell should have at least eight memory DIMMs (Dual
Inline Memory Modules), for a minimum of 4 GB RAM per cell
at first release.
Explanation: Memory is packaged in four-DIMM increments. A
failure of one DIMM will cause the remaining three in the package to
shut down. If the cell has only four DIMMs in all (2 GB at first
release), it will be unbootable until the defective memory is replaced,
whereas a cell that has at least eight DIMMs (4 GB at first release)
can be rebooted even if four DIMMs are inactive.
• Add memory to cells in increments of eight DIMMs (two
packages of four DIMMs each).
At first release, this means each cell’s total memory should be evenly
divisible by 4 GB.
Explanation: There are two memory busses on the cell board. When
the busses are loaded equally, memory traffic can be spread evenly
across them to provide the maximum bandwidth.