Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm List-Subscribe: List-Archive: List-Post: List-Help: , Sender: cygwin-owner@cygwin.com Mail-Followup-To: cygwin@cygwin.com Delivered-To: mailing list cygwin@cygwin.com Date: Mon, 19 May 2003 13:59:13 -0400 From: Christopher Faylor To: cygwin@cygwin.com Subject: Re: SPARSE files considered harmful - please revert Message-ID: <20030519175913.GA24066@redhat.com> Reply-To: cygwin@cygwin.com Mail-Followup-To: cygwin@cygwin.com References: <16072.6666.10124.338022@gargle.gargle.HOWL> <00f301c31e12$c29efdb0$6400a8c0@FoxtrotTech0001> <00be01c31e15$944d0d50$78d96f83@pomello> <005601c31e26$77671260$6400a8c0@FoxtrotTech0001> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <005601c31e26$77671260$6400a8c0@FoxtrotTech0001> User-Agent: Mutt/1.4.1i On Mon, May 19, 2003 at 12:46:19PM -0400, Bill C. Riemers wrote: > >> Um? By my understanding, making a file sparse can never be dangerous. It >can >> cause sub-optimal performance, but code reading the file doesn't have to >be >> aware of anything special - the OS takes care of it. > >I remember there use to be a warning the man page that file system holes can >cause seek offsets to be wrong for programs that do seek's across or into >hole boundries. The original Linux code only handled when code was loaded >as a result of an mmap which happens for exec's and dlopen. It could be by >now these restrictions have been eliminated. I notice the latest GNU cp >info page lists sparse files a filesystem capacity not a kernel capability, >and the logic for --sparse=auto simply copies a file as-is, nothing smart >like checking for the execution bit. > >I looked through the NTFS document on MSDN. It seems at least for NTFS >there is no restriction on what types of files can be sparse. Of course, if >you make files sparse that are going to be accessed with RW operations, you >are going to fragment the file. I think you need to read the documentation a little more closely. Either that or provide references to the parts of the documentation that says that normal RW operations would fragment a sparse file. -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/