From owner-freebsd-questions@FreeBSD.ORG Sat Nov 19 00:24:46 2005 Return-Path: X-Original-To: questions@freebsd.org 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 CFC7A16A41F for ; Sat, 19 Nov 2005 00:24:46 +0000 (GMT) (envelope-from mi+mx@aldan.algebra.com) Received: from vms040pub.verizon.net (vms040pub.verizon.net [206.46.252.40]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6D52F43D46 for ; Sat, 19 Nov 2005 00:24:46 +0000 (GMT) (envelope-from mi+mx@aldan.algebra.com) Received: from corbulon.video-collage.com ([151.204.231.237]) by vms040.mailsrvcs.net (Sun Java System Messaging Server 6.2-4.02 (built Sep 9 2005)) with ESMTPA id <0IQ600MADEGXDT11@vms040.mailsrvcs.net> for questions@freebsd.org; Fri, 18 Nov 2005 18:24:42 -0600 (CST) Received: from mteterin.us.murex.com (195-11.customer.cloud9.net [168.100.195.11]) by corbulon.video-collage.com (8.13.4/8.13.1) with ESMTP id jAJ0OWMI004672 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Fri, 18 Nov 2005 19:24:33 -0500 Received: from mteterin.us.murex.com (mteterin@localhost [127.0.0.1]) by mteterin.us.murex.com (8.13.4/8.13.4) with ESMTP id jAJ0OJSL080171 for ; Fri, 18 Nov 2005 19:24:19 -0500 Received: from localhost (localhost [[UNIX: localhost]]) by mteterin.us.murex.com (8.13.4/8.13.4/Submit) id jAJ0OHcV080170 for questions@freebsd.org; Fri, 18 Nov 2005 19:24:17 -0500 Date: Fri, 18 Nov 2005 19:24:17 -0500 From: Mikhail Teterin To: questions@freebsd.org Message-id: <200511181924.17282.mi+mx@aldan.algebra.com> Organization: Virtual Estates, Inc. MIME-version: 1.0 Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit Content-disposition: inline X-Virus-Scanned: ClamAV devel-20050525/1179/Fri Nov 18 12:33:40 2005 on corbulon.video-collage.com X-Virus-Status: Clean X-Scanned-By: MIMEDefang 2.43 X-Authentication-warning: mteterin.us.murex.com: mteterin set sender to mi+mx@aldan.algebra.com using -f User-Agent: KMail/1.8.2 Cc: Subject: throttling NFS writes X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 19 Nov 2005 00:24:46 -0000 Hi! We have an unusual problem with NFS writes being _too fast_ for our good. The system is accepting database dumps from NFS-clients and begins compressing each dump as soon, as it begins arriving (waiting for more via kevent, if needed). The NFS-clients (database servers) run on slow Sparc processors and can not be bothered to compress their data... The setup works quite well, if the to-be compressed data is still in memory, when the compressor gets to it. "Unfortunately", those Sparc systems have rather fast I/O rates and manage to write their dumps faster, than the compressor can compress it. When this happens, the overall performance of the backup script goes down through the floor :-(, because it forces the disk to read the middle of a file (for compression), while data keeps arriving (from the NFS-client) at the end of it... So we'd like to stall the client's dumping, so that the compressor can keep up. Short of limiting NFS-bandwidth via ipfw, is there a way to control NFS speed dynamically? The uncompressed dumps are _huge_, although they compress very well. So we can not just accept all of them first and then start compressing -- we don't have enough room. There is enough to keep about 3 full-dumps worth of compressed data, but even a single uncompressed full dump would not fit... -mi