User Guide

IBM

Power

Power10 Quick-start Guide – E1080 Memory Performance

Minimum Memory

• For each processor socket a minimum of 8 of the 16 DDIMMs are populated

• In a node, a minimum of 32 of 64 for the DDIMMs are populated

• In a 4-Node system, a minimum of 128 of the 256 DDIMMs are populated

DDIMM Capacity

Theoretical Max

Bandwidth

32GB, 64 GB (DDR4 @ 3200 Mbps) 409 GB/s

128GB, 256 GB (DDR4 @ 2933 Mbps) 375 GB/s

DDIMM Plug Rules

• Meet minimum memory allowed (each processor socket a minimum of 8 of the 16

DDIMMs are populated)

• All DDIMMs under each processor have to be same capacity

• Feature upgrades will be offered in increments of 4 DDIMM’s, all of which have the

same capacity.

• The only valid number of DDIMM’s plugged into sites connected to a given processor

module is 8 or 12 or 16.

Memory Bandwidth

Memory Performance

• System performance improves as the amount of memory is spread across more DDIMM

slots.

For example, if 1TB is needed in a Node, it is better to have 64 x 32GB DDIMMs than

to have 32 x 64GB DDIMMs.

• Plugging DDIMMs that are all the same size will provide the highest performance

• System performance improves as more quads match each other

• System performance improves as more processor DDIMMs match each other

• System performance improves on a multi drawer system if memory capacity between

drawers are balanced.

Summary

• For the best possible performance, it is generally

recommended that memory be installed evenly across all

system node drawers and all processor sockets in the

system. Balancing memory across the installed system

planar cards enables memory access in a consistent manner

and typically results in better performance for your

configuration.

• Though maximum memory bandwidth is achieved by filling all

the memory slots, plans for future memory additions should

be considered when deciding which memory feature size to

use at the time of initial system order.