From owner-freebsd-questions Wed Jan 22 20: 1:51 2003 Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 78E7237B401 for ; Wed, 22 Jan 2003 20:01:50 -0800 (PST) Received: from anubis.dweebsoft.com (anubis.dweebsoft.com [64.81.58.36]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0219743EB2 for ; Wed, 22 Jan 2003 20:01:50 -0800 (PST) (envelope-from deckenberg@dweebsoft.com) Received: from daxhome (daxhome.dweebsoft.com [192.168.10.10]) by anubis.dweebsoft.com (8.12.6/8.12.6) with SMTP id h0N41feC029847; Wed, 22 Jan 2003 20:01:41 -0800 (PST) Message-ID: <0a8401c2c294$22e6e1e0$0a0aa8c0@dweebsoft.com> From: "Dax Eckenberg" To: "Noah Garrett Wallach" , "Dan Nelson" Cc: , "canton" References: <20030122191542.J76039@typhoon.enabled.com> <20030123032816.GA1799@dan.emsphone.com> <20030122193922.C76039@typhoon.enabled.com> Subject: Re: iostat - define Kilobits per transfer Date: Wed, 22 Jan 2003 20:01:35 -0800 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4920.2300 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4920.2300 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG > > > I currently have an IDE drive that has the capacity to do 128KB/t and > > > a SCSI drive 64KB/t. Are these stats in fact showing me that there > > > is a limitation with the SCSI drive? Are my file transfering > > > capaibilities less with the SCSI drive? I suppose what do I need to > > > look for in the spcifications when choosing new drives so this does > > > not happen again? > > > > FreeBSD's SCSI layer has a cap of 64k per transaction (apparently > > because ancient ISA adapters could not do more than 64k), and the ATA > > layer has a cap of 128k. You won't see a difference using regular > > disks. A 20MB/sec transfer rate comes out to ~300 64K > > transactions/sec, which most systems should be able to handle with no > > problems. > > > so what exactly does KB per transaction mean? what happens if I am > handling 300 concurrent users with 160Kbit encoded audio streams - could I > in fact do this on this machine? or will I be limited by the 64KB/t > issue? > 300 x 160Kbit = approx. 46Mbit/sec. A new-ish SCSI drive should be able to easily pump out in excess of 200 Mbit/sec. Your bottleneck will be your ethernet adapter long before your local storage. Unless your app is designed very poorly. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message