SUMMARY: RAM Interleaving Basics

From: Tim Evans (
Date: Tue Jul 25 2000 - 12:44:50 CDT

Last week, I asked:

>I'm looking for basic documentation on memory interleaving on
>Enterprise-class (E3000 and up) systems. SunSolve's site has
>nothing in its
>White Papers section, nor can I find anything useful in
>AnswerBooks. Even
>the Open Boot Prom manuals don't mention the
>'memory-interleave' parameter.
Thanks to:
Virdi, Amarjeet Singh (Amarjeet)** CTR ** []
Scott Clark - SSE []

I had a couple of references to Brian Wong's book, _Configuration and
Capacity Planning for
Solaris Servers_, and another to Adrian Cockroft's book _Sun Performance

Ravi provided the most useful info about the OpenBoot Prom:

>I think in E-3x00/4x00/5x00 memory interleaving can be either min or max.
>In each CPU board you have 16 DIMM slots and you will have to install in
>pairs. Based on this, I am of the opinion that you can use either
>I am not completely sure, so try it with a value you are comfortable and
>/usr/platform/`uname -i`/prtdiag -v to see how the interleaving is done.
>you may be able to do either min or max, min being the choice if you also
>to use DR.
>In E-450/250 you can set it to 2,4,1 or max, depending on how your banks
>are populated. Also, same size DIMMs need to be used across all banks
>for interleaving to work properly.

Also, I had entered a support request on our Sun support contract for
information on interleaving. A Sun engineer sent me an SRDB document
(#21869) which gives extended examples of how interleaving works on various
combinations of memory boards. The document is, however, marked
confidential to contract customers only; those of you who have support can
look this up on SunSolve.

Tim Evans, T.Rowe Price Investment Technologies	|
11550 Cronridge Drive, Owings Mills, MD 21117
410-345-3174; Pager: 800-946-4646, PIN 1716638; FAX 410-345-3030

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