From owner-freebsd-hackers Wed Mar 6 9:14:56 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from bingnet2.cc.binghamton.edu (bingnet2.cc.binghamton.edu [128.226.1.18]) by hub.freebsd.org (Postfix) with ESMTP id 7281037B402 for ; Wed, 6 Mar 2002 09:14:51 -0800 (PST) Received: from onyx (onyx.cs.binghamton.edu [128.226.140.171]) by bingnet2.cc.binghamton.edu (8.11.6/8.11.6) with ESMTP id g26HETm03523; Wed, 6 Mar 2002 12:14:29 -0500 (EST) Date: Wed, 6 Mar 2002 12:12:44 -0500 (EST) From: Zhihui Zhang X-Sender: zzhang@onyx To: Peter Edwards Cc: "Brian T.Schellenberger" , Lars Eggert , "Rogier R. Mulhuijzen" , Julian Elischer , freebsd-hackers@FreeBSD.ORG Subject: Re: A weird disk behaviour In-Reply-To: <3C8648F5.1EC1E4EE@openet-telecom.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Wed, 6 Mar 2002, Peter Edwards wrote: > Zhihui Zhang wrote: > > > > > ... I also do not read anything during the partial block write, > > and I think the disk controller should not do that either. > > If you do a partial block write, surely at some point the block must be read > in order to preserve that segment of data you are _not_ overwriting? First off, I am not writing through any file system. I access the raw device directly. Secondly, the bytes written are always a multiple of 512 bytes. If one sector is the I/O unit of a disk controller, why should it read anything to prevent overwritten? -Zhihui To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message