[NTLUG:Discuss] VM Ware -- memory questions

[Bryan J. Smith]

From:  John Thomas 
> Anyway, I'm looking at a Dell workstation since Dell
> now supports Linux 
(RH Enterprise WS). 

I have a problem with tier-1 OEMs that are exclusively PC focused.
Despite being more funded by Intel, the reason why Dell offered Linux on the desktop in 1999-2000,
many of us in the semiconductor industry remember the "games played" by Microsoft at Dell in 1999-2000.

> Dell sells 533 MHz ECC memory but recommends
> the 400 MHz Non-ECC memory.
> 1.  Is the 400 MHz memory recommended because the
> front-side bus speed  is an intergral multiple of this value,
> thus making memory references more efficient?

Synchronous CPU-Memory-I/O in the Intel GTL (Pent), GTL+ (PPro-P3/Xeon) and AGTL+ (P4/Xeon) interconnect is ideal.
So synchronous rate for memory may depend on the CPU. 

Also note that latency is another consideration.
Many "higher DTR (Data Transfer Rate)" memory modules stay competitive by using modules with DRAM access times that are worse than "slower DTR.".
The synchronous timing is NOT the DRAM latency, a common mistake made by enthusiast sites.

> If so, then that part of the recommendation makes since.

Dell's not just saying that Linux is incompatible with it, correct?
That's the stupid stuff I ran into back in 1999-2000.

> 2.  I'm planning on 1-2 GB of RAM,
> so I'd like to be comforted that the  Non-ECC memory
> is reliable running Linux and VM Ware.

Registered ECC is always a good idea when stability is concerned.
Some Intel chipsets do not support registered and/or ECC.
I haven't studied the Intel engineering docs on the i865/875 or i915/925
(only older chipsets or chipsets licensed from ServerWorks like i7500 series).

Otherwise, I'm curious why they would be saying that.
Just know mysuspicions are justified given the instances I, and others I confirmed with, in 1999-2000 with Dell.

-- 
Bryan J. Smith (currently mobile)
b.j.smith at ieee.org