From owner-freebsd-scsi Thu Nov 2 16:53:36 2000 Delivered-To: freebsd-scsi@freebsd.org Received: from thelab.hub.org (CDR20-53.accesscable.net [24.138.20.53]) by hub.freebsd.org (Postfix) with ESMTP id 9D10437B4C5 for ; Thu, 2 Nov 2000 16:53:33 -0800 (PST) Received: from localhost (scrappy@localhost) by thelab.hub.org (8.11.1/8.11.1) with ESMTP id eA30pEO63058; Thu, 2 Nov 2000 20:51:14 -0400 (AST) (envelope-from scrappy@hub.org) X-Authentication-Warning: thelab.hub.org: scrappy owned process doing -bs Date: Thu, 2 Nov 2000 20:51:14 -0400 (AST) From: The Hermit Hacker To: "Justin T. Gibbs" Cc: Tom Samplonius , freebsd-scsi@FreeBSD.ORG Subject: Re: iostat: tps for SCSI drives ... In-Reply-To: <200011030020.eA30KFa90886@aslan.scsiguy.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Thu, 2 Nov 2000, Justin T. Gibbs wrote: > >So, what exactly does supporting 64, or 128, tags on a drive > >provide? > > Since modern drives perform seek optimization and command coalescing, > it will usually result in fewer or shorter seeks and thus better > throughput. How "smart" is it? In a multi-user system, I imagine that Cmd0->Cmd5 could be for information that UserA needs, while Cmd6->Cmd7 is for something UserB needs ... I imagine this would have to be "on the drive", but can they feed back information for Cmd6->Cmd7 while its processing Cmd0->Cmd5? Or is it purely FIFO? To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message