From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: 3ware escalade vs software raid, from a different jeff Date: Thu, 19 Feb 2004 23:26:16 -0500 Sender: linux-raid-owner@vger.kernel.org Message-ID: <40358C68.80205@pobox.com> References: <200402191958.i1JJwP225623@bzs.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <200402191958.i1JJwP225623@bzs.org> To: michael@insulin-pumpers.org Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Michael wrote: > Bear in mind that what you are calling "true hardware raid" is really > a microprocessor programmed to do the raid algorithims. Usually these > microprocessors are stretched to the limit to handle the throughput > of modern udam drives. I don't know but I suspect that the small > overhead use in the mmu for software raid has far more and faster > throughput than any of these dedicated microprocessors..... and, you > can see the code and know it is bug free or will be if you report the Nod... many hardware RAIDs are turning out this way. A certain vendor whose name does -not- start with 'A' manages to make their hardware RAID perform so poorly, it is _half_ the speed of a software RAID using the same drives, on a single non-RAID Adaptec SCSI controller. Most hardware RAID isn't 100% ASIC, but rather a general ASIC and firmware with the RAID code in it. OTOH, hardware RAID really wins for situations like RAID-1, where you can -halve- the amount of data going across the PCI bus versus software RAID. Jeff