Date: Thu, 4 May 2000 21:06:35 +0200 From: Vallo Kallaste <vallo@matti.ee> To: Mike Smith <msmith@freebsd.org> Cc: Parag Patel <parag@cgt.com>, freebsd-stable@FreeBSD.ORG Subject: Re: How good is AMI MegaRAID support? Message-ID: <20000504210635.A8681@myhakas.matti.ee> In-Reply-To: <200004300431.VAA00672@mass.cdrom.com>; from msmith@freebsd.org on Sat, Apr 29, 2000 at 09:31:50PM -0700 References: <93707.957044958@pinhead.parag.codegen.com> <200004300431.VAA00672@mass.cdrom.com>
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On Sat, Apr 29, 2000 at 09:31:50PM -0700, Mike Smith <msmith@freebsd.org> wrote: > > Out of curiosity, how would a PCI-RAID (SCSI) adapter compare with > > vanilla PCI-SCSI cards and vinum? It seems to me that the host CPU(s) > > are much faster than the processors on the PCI-SCSI adapters. Or are > > both of these "fast-enough" and thus performance differences are largely > > an irrelevent consideration? (They both have similar software issues > > but I suspect vinum is easier to debug. :) > > All other things being equal, software RAID is going to be faster. (ie. > same disks, same # of SCSI channels, etc.) The hardware solution's sell > there is: > > - better support/functionality (enclosure management, etc.) > - better survivability (battery-backed cache) > > Plus you get a stack of SCSI channels onboard the card. Are you sure? I think the upcoming IBM ServeRaid version 4 adapters will have PowerPC 750 processor which outperforms current host processors easily? Anyway I think for degraded mode you'll definitely need separate processing unit to offload parity calculations from host processor, else the system will calculate parity not service users. That's theory, of course, but it seems so obvious. Am I missing something? All this discussion seems quite unnecessary in that light for me. -- Vallo Kallaste vallo@matti.ee To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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