From owner-freebsd-questions Wed Jan 22 19:28:20 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 52DF337B401 for ; Wed, 22 Jan 2003 19:28:19 -0800 (PST) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id BD0CE43F13 for ; Wed, 22 Jan 2003 19:28:18 -0800 (PST) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.12.6/8.12.6) id h0N3SGwj053525; Wed, 22 Jan 2003 21:28:16 -0600 (CST) (envelope-from dan) Date: Wed, 22 Jan 2003 21:28:16 -0600 From: Dan Nelson To: Noah Garrett Wallach Cc: freebsd-questions@FreeBSD.ORG Subject: Re: iostat - define Kilobits per transfer Message-ID: <20030123032816.GA1799@dan.emsphone.com> References: <20030122191542.J76039@typhoon.enabled.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030122191542.J76039@typhoon.enabled.com> X-OS: FreeBSD 5.0-CURRENT X-message-flag: Outlook Error User-Agent: Mutt/1.5.3i 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 In the last episode (Jan 22), Noah Garrett Wallach said: > can somebody give me a better understanding of what the iostat output > is decribing in the KB/t column. It might be really simple but > figured I';d ask, if in fact further clarification can be given. > > typhoon% iostat 1 > tty da0 da1 acd0 > tin tout KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s us ni sy in > 0 21 0.00 0 0.00 0.00 0 0.00 0.00 0 0.00 1 0 1 0 > > do drive specifications generally contain KB/t information or statistics? When there is disk activity, yes. Try running a couple du's or extract a couple ports, then run iostat in another window. > 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. -- Dan Nelson dnelson@allantgroup.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message