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Date:      Tue, 2 May 2000 00:12:15 +0200
From:      Brad Knowles <blk@skynet.be>
To:        Parag Patel <parag@cgt.com>, Mike Smith <msmith@FreeBSD.ORG>
Cc:        freebsd-stable@FreeBSD.ORG
Subject:   Re: How good is AMI MegaRAID support?
Message-ID:  <v04220806b533b0ef8c49@[195.238.24.94]>
In-Reply-To: <93707.957044958@pinhead.parag.codegen.com>
References:  <93707.957044958@pinhead.parag.codegen.com>

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At 2:49 PM -0700 2000/4/29, Parag Patel 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.

	In fact, this is precisely what Greg Lehey and some others have 
told me, and my own experience has confirmed this.

>                                                                 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. :)

	How fast is fast enough?  Do you need a disk subsystem that can 
handle bursts of ~2500 USENET news history database lookups per 
second?  What would it take to get to that level?  Do you need to see 
rawio read performance (average tranfer size of one sector w/ 64 
simultaneous processes) of around 5,000 read operations per second? 
If so, then I've only barely managed to get there.

	Sure, vinum will be easier to debug.  The only issue is how much 
debugging do you believe that the hardware RAID vendors have done 
before they ship their product, versus how much debugging do you 
think vinum gets?  Myself, I'm learning to put a lot more trust in 
Greg....

--
   These are my opinions -- not to be taken as official Skynet policy
======================================================================
Brad Knowles, <blk@skynet.be>                || Belgacom Skynet SA/NV
Systems Architect, Mail/News/FTP/Proxy Admin || Rue Colonel Bourg, 124
Phone/Fax: +32-2-706.13.11/12.49             || B-1140 Brussels
http://www.skynet.be                         || Belgium


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