Date: Tue, 1 Apr 2008 00:18:31 +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: <9bbcef730803311518h5e75a18dq1f11189ddae8b75c@mail.gmail.com> In-Reply-To: <47F15F3C.9060100@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>
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On 01/04/2008, Scott Long <scottl@samsco.org> wrote: > If you have a RAID controller in front of the disks then the effects of > TCQ are hidden from the OS; it might ultimately make the controller > complete requests faster, but the controller already looks to the OS > like a disk with a really deep queue. When you're dealing directly with > the disks then TCQ/NCQ is required in order for batching of concurrent > requests to occur. Thanks. I thought TCQ is also used between the OS and the controller (since the RAID array is presented to the OS as opaque...).home | help
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