From owner-freebsd-hardware Thu Mar 26 08:23:15 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id IAA08444 for freebsd-hardware-outgoing; Thu, 26 Mar 1998 08:23:15 -0800 (PST) (envelope-from owner-freebsd-hardware@FreeBSD.ORG) Received: from clifford.inch.com (omar@clifford.inch.com [207.240.140.163]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id IAA08428 for ; Thu, 26 Mar 1998 08:23:02 -0800 (PST) (envelope-from omar@clifford.inch.com) Received: (from omar@localhost) by clifford.inch.com (8.8.5/8.8.5) id LAA29859; Thu, 26 Mar 1998 11:20:20 -0500 Message-ID: <19980326112020.04093@clifford.inch.com> Date: Thu, 26 Mar 1998 11:20:20 -0500 From: Omar Thameen To: freebsd-hardware@FreeBSD.ORG Subject: Re: DPT and ECC memory References: <19980323193054.62953@clifford.inch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.81 In-Reply-To: <19980323193054.62953@clifford.inch.com>; from Omar Thameen on Mon, Mar 23, 1998 at 07:30:54PM -0500 Sender: owner-freebsd-hardware@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Mon, Mar 23, 1998 at 07:30:54PM -0500, I wrote: > > Is there anything special about the DPT ECC memory that they sell, [for their RAID controllers] > apart from it being ECC? DPT lists the price at over $1100 for 16M, > but my vendor is telling me that he sells 32M of 70 pin ECC memory for > around $70. Why the disparity? Here's the company line I got from DPT: DPT ECC Regular ECC ------------------------------------------------------------------------ 1. It will correct full 32 bit Based on Hamming Coding. word errors in a 512 byte page 2. Hardware implemetation - Must access data in 4 or 8 byte no overhead on Motorola chunks processor on the HBA - only when corrections needed. (not 512 byte chunks) 3. Corrects multi-bit errors Corrects only single byte. in word. 4. Overhead -3% (Overhead Has 12.5 to 21.9% overhead +system resource usage) 5. Raid Tower hot swaps can cause (sometimes) a glitch and crash the system _ DPT ECC SIMMS can prevent this. (electrical spike becomes odd bit which is taken care of by correction). I can't comment on the the claims, but at >$1100 vs. $70, we'll be going with regular ECC. -- Omar To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hardware" in the body of the message