Date: Tue, 1 Apr 2008 00:48:14 +0200 From: "Ivan Voras" <ivoras@freebsd.org> To: "Scott Long" <scottl@samsco.org> Cc: freebsd-current@freebsd.org Subject: Re: Are large RAID stripe sizes useful with FreeBSD? Message-ID: <9bbcef730803311548o4a2d665cwdadaf87f6b719030@mail.gmail.com> In-Reply-To: <47F1659E.8020001@samsco.org> References: <fsr7fb$hl0$1@ger.gmane.org> <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>
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On 01/04/2008, Scott Long <scottl@samsco.org> 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?
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