From owner-freebsd-current@FreeBSD.ORG Mon Mar 31 22:48:15 2008 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1D11F1065676 for ; Mon, 31 Mar 2008 22:48:15 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: from rv-out-0910.google.com (rv-out-0910.google.com [209.85.198.186]) by mx1.freebsd.org (Postfix) with ESMTP id A9EC38FC16 for ; Mon, 31 Mar 2008 22:48:14 +0000 (UTC) (envelope-from ivoras@gmail.com) Received: by rv-out-0910.google.com with SMTP id g13so1203493rvb.43 for ; Mon, 31 Mar 2008 15:48:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth; bh=4WMgfTEMvGyueI+oJVpMLU6fgTqKglFn7/K22uwf7/8=; b=rzYRLqKJq/l+0Vxjtsjo3AIr5sJOwDlrqFlM19DBXK9eTYewGt6oQc3aq9hVL3WLOhcmJcyde/oXeeCnzHVvjbbXyxornWgGVy3Y820Y3nLoi1asakI8KsCDPjNqj2oTlQnnT8kAk9BzsrSxpYtSSK3eLUrGaOW82U9JQwGYrzw= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=message-id:date:from:sender:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references:x-google-sender-auth; b=Sr9MhinsL0w8bAMrsO/PQ8JXCGH7pcJCAEu6kSouIfYsO6dQPJF0S6GWMw20d4zo+mu5JrD/Ch1wejzJR+0VogGJGKM7PUmUp54fi4BryzxvTNSJLdC7Rsk4RQy/vdQMwsZfZ+ubC0RW51x/OODiKsfPpqwoCUSUe90C0KLEztI= Received: by 10.140.207.2 with SMTP id e2mr3833535rvg.144.1207003694216; Mon, 31 Mar 2008 15:48:14 -0700 (PDT) Received: by 10.141.212.1 with HTTP; Mon, 31 Mar 2008 15:48:14 -0700 (PDT) Message-ID: <9bbcef730803311548o4a2d665cwdadaf87f6b719030@mail.gmail.com> Date: Tue, 1 Apr 2008 00:48:14 +0200 From: "Ivan Voras" Sender: ivoras@gmail.com To: "Scott Long" In-Reply-To: <47F1659E.8020001@samsco.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <47F147D8.3030905@samsco.org> <9bbcef730803311409ha25effam9dd522c9084783ad@mail.gmail.com> <47F15772.5010104@samsco.org> <9bbcef730803311434s48d3269cs1e8ae0fd1eb7ffc3@mail.gmail.com> <47F15F3C.9060100@samsco.org> <9bbcef730803311518h5e75a18dq1f11189ddae8b75c@mail.gmail.com> <47F1659E.8020001@samsco.org> X-Google-Sender-Auth: ea744b68f6fd651e Cc: freebsd-current@freebsd.org Subject: Re: Are large RAID stripe sizes useful with FreeBSD? X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 31 Mar 2008 22:48:15 -0000 On 01/04/2008, Scott Long wrote: > TCQ is a protocol specific to parallel SCSI that involves the use of > protocol messages and control signals found only on a parallel SCSI bus. > PCI RAID controllers that present a SCSI interface to the OS don't use > real TCQ to communicate between the OS and the controller. Even though > these kinds of controllers use the SCSI command protocol, they still use > a custom device-specific low-level communication protocol that handles > the transfer and queuing of commands. External RAID > controllers/enclosures do use the appropriate SCSI/SAS/FC/SATA bus > queuing mechanism, but I'm not sure if that's what you're talking about > here. Your're right, I'm not. On further thought it's logical - if RAID controllers talked plain SCSI to the OS there wouldn't be a need for specific drivers, right?