From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Peterson Subject: Re: New feature Idea Date: Wed, 13 Aug 2008 13:06:10 -0600 Message-ID: <48A330A2.6020306@gentoo.org> References: <48A320A0.80609@gmail.com> <48A32DDE.8070203@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Morey Roof , linux-btrfs@vger.kernel.org To: jim owens Return-path: In-Reply-To: <48A32DDE.8070203@hp.com> List-ID: jim owens wrote: > Don't do it!!! > > OK, I know Chris has described some block sharing. But I hate it. > > If I copy "resume" to "resume.save", it is because I want 2 copies > for safety. I don't want the fs to reduce it to 1 copy. And > reducing the duplicates is exactly opposite to Chris's paranoid > make-multiple-copies-by-default. Hi Jim, My thoughts on what you are saying is that it is not generally a good idea to assume any filesystem will lay things out in any specific way, including whether it has one-to-one mapping of files to blocks. In other words, making a copy of a file on the same filesystem for safety reasons (unless you are modifying a file and want a backup of its old state, like emacs' ~ files) is probably not a great habit to get into. The implementation details of how a filesystem makes things safer should be behind-the-scenes (like checksums, multiple-copies-by-default, mirroring, etc.). That way, you can simply rely on the filesystem to manage protection of your data rather than going to the effort of managing multiple copies of files yourself for that reason. -Joe