[SunRescue] (Help!) Problems with Solaris 8 and SPARCServer 1 000E? [Late entry]

[James Lockwood]

On Thu, 4 Jan 2001, Garten, David N., CTR, OSD/P&R wrote:

> 	Last item: Memory should be installed symmetrically across all
> boards - Bank0 on all installed boards, then bank1 on all boards, etc.
> Since it goes in 128Meg increments, you might try 256 on each board (banks 0
> and 1) and hold off on the last bank until you have another 128Meg.  

This is an efficiency consideration (memory symmetry), not a requirement.
Memory is tied to the XDbus and not to individual boards, but the latancy
to memory on the same board is lower.  XDbus contention will be reduced if
more accesses are local, and assuming that you have a relatively even
distribution of processes across CPUs it makes sense to spread the memory
out as well.

That said, it's probably better to use additional memory somewhere than
not at all.  You may generate more XDbus traffic but the increased RAM
should more than compensate for it in most cases.  This is in contrast to
banked memory interleaving (such as on the Ultra 450), where adding
additional memory can break an interleave completely and decrease
bandwidth to the entire system.

-James