[NTLUG:Discuss] SunFire X2200 M2 memory strangeness

[Eric Schnoebelen]

Ralph Green writes:
- Howdy,
-   I had a strange experience with memory in a Sun server last night.
- This is a donated server to a charity, and I am trying to see if I can
- make it useful and a bit quieter.  I have some memory chips pulled
- from other servers.  The memory in the Sun was 4 1 GB sticks(DDR2, ECC
- registered, PC2-5300 speed).  My extra sticks are bigger(2GB) and
- slower(DDR2, ECC registered, PC2-3200 speed).  I tried putting 4 of
- the 2 GB in each bank, but it would not boot at all.  I ended up
- putting the 4 1 GB sticks in memory bank 0 and 6 2GB sticks in memory
- bank 1 and it seems to run fine.  This leads to a couple of questions
- and I wonder if people have seen similar behavior in other computers.

I have an X2200M2 in service here, so maybe I can provide some
assistance.

-  1. Why would the bigger sticks only work in memory bank 1?

Are you sure the spec's of the 2Gb devices are supported by the
X2200M2? All the documentation I've found
(http://www.crucial.com/store/listparts.aspx?model=Sun%20Fire%20X2200%20M2&Cat=RAM
and http://library.cirr.com/SUN/X2200M2/ -- my own copy of
Oracle's docs for the X220) say only PC2-5300 is supported.

I suspect they only worked in bank 1 because they weren't being
as heavily probed as bank 0, or they had long enough to respond
to the probes.

-  2. Is there any problem running 3 times as much memory in one bank?

I wouldn't think there'd be any problems, assuming the memory
all worked..

But, I really expect some serious problems once you get the
system under memory load.

-  I am planning on using this as a database server and I am looking
- forward to being able to have 16 GB of RAM and 4 pretty good CPUs to
- test with.  The server will go back to the charity, but I get to play
- with it a while.

If the charity would rather have money for the unit, I would be
interested in aquiring it as a spare..

I hope the above helps,	
	Eric

--
Eric Schnoebelen		eric at cirr.com 		http://www.cirr.com
      "Memory is like an orgasm. It's a lot better if you don't
	  have to fake it." -Seymore Cray, on virtual memory