From owner-freebsd-questions@FreeBSD.ORG Wed Dec 3 00:02:26 2003 Return-Path: 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 6668D16A4CE for ; Wed, 3 Dec 2003 00:02:26 -0800 (PST) Received: from criton.w617.com (criton.w617.com [210.18.194.24]) by mx1.FreeBSD.org (Postfix) with ESMTP id 80F9B43FBF for ; Wed, 3 Dec 2003 00:02:21 -0800 (PST) (envelope-from kevin@w617.com) Received: from MINB1466 (dhcp81 [192.168.240.81]) by criton.w617.com (8.9.3/8.9.3) with SMTP id SAA74358 for ; Wed, 3 Dec 2003 18:02:17 +1000 (EST) (envelope-from kevin@w617.com) From: "Kevin Fleming" To: Date: Wed, 3 Dec 2003 18:03:50 +1000 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: dump performance - 4.6-RELEASE #0 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Dec 2003 08:02:26 -0000 I've done numerous tests with dump and different buffer sizes etc, but the maximum speed I can read from disk is approximately 14MB/s (measured by iostat). cpio / tar etc can read from disk at over 30MB/s .. Dump seems to spawn children (presumably for better IO) - is it possible to tweak the number of children for better IO performance. I can write to my tape unit at a sustained 25MB/s (AIT-3 on an LVD interface), so I'm wasting tape and time. Kevin