From owner-freebsd-questions Wed Jan 22 19:44:52 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 4FB5137B401 for ; Wed, 22 Jan 2003 19:44:51 -0800 (PST) Received: from typhoon.enabled.com (typhoon.enabled.com [216.218.248.34]) by mx1.FreeBSD.org (Postfix) with ESMTP id F0D0743F18 for ; Wed, 22 Jan 2003 19:44:50 -0800 (PST) (envelope-from sleek@enabled.com) Received: from localhost (localhost.enabled.com [127.0.0.1]) by typhoon.enabled.com (8.12.7/8.12.7) with ESMTP id h0N3iM7C076459; Wed, 22 Jan 2003 19:44:22 -0800 (PST) (envelope-from sleek@enabled.com) Date: Wed, 22 Jan 2003 19:44:22 -0800 (PST) From: Noah Garrett Wallach To: Dan Nelson Cc: freebsd-questions@FreeBSD.ORG, canton Subject: Re: iostat - define Kilobits per transfer In-Reply-To: <20030123032816.GA1799@dan.emsphone.com> Message-ID: <20030122193922.C76039@typhoon.enabled.com> References: <20030122191542.J76039@typhoon.enabled.com> <20030123032816.GA1799@dan.emsphone.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII 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? - Noah > > -- > Dan Nelson > dnelson@allantgroup.com > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message