Re: [PLUG] RAID6 or RAID5+HS?

["Keith C. Perry" <kperry@daotechnologies.com>]

I think the language is getting in the way here.  My fault since I'm used to thinking about this as processors and cores.  When I say cpu or processor, that is usually what is referred to as a "socket" today.  You'll see settings for those when its comes to cluster software or virtualization configuration.  In today's world cores are cpus- totally agree there.  From the Linux point of view there is a different in the sense that Linux knows how many sockets a system has online as well as how many cores are available in that socket.

Practically speaking, if you have a system with multiple sockets online and you don't do a NUMA config (many people don't) then the distinction doesn't matter- you wouldn't even know you have a 2-way or 4-way system unless you looked at "numa --hardware" because /proc/cpuinfo and /proc/meminfo (or free) are going to show you everything available and treat all the resources with equal availability and planning because they are all in node 0.

I think Linux probably does make proper use of this but it would be interesting to see a whitepaper from AMD on such matters.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 
Keith C. Perry, MS E.E. 
Owner, DAO Technologies LLC 
(O) +1.215.525.4165 x2033 
(M) +1.215.432.5167 
www.daotechnologies.com

----- Original Message -----
From: "Rich Freeman" <r-plug@thefreemanclan.net>
To: "Philadelphia Linux User's Group Discussion List" <plug@lists.phillylinux.org>
Sent: Wednesday, August 24, 2016 3:59:27 PM
Subject: Re: [PLUG] RAID6 or RAID5+HS?

On Wed, Aug 24, 2016 at 3:46 PM, Keith C. Perry
<kperry@daotechnologies.com> wrote:
>
> The main point is that NUMA is about about processors, not cores and there are "server" boards that can make use of real NUMA nodes.  Cool stuff to play around with especially in the context of CPUsets, cgroups and other container or VM tech.
>

A core IS a processor, it just may or may not share some components
like a memory controller with other cores.  My understanding is that
AMD processors typically operate in unganged mode, with different
cores having direct access to different memory channels.  However, I'm
not sure that Linux takes advantage of this.

-- 
Rich
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