On Wed, 2008-08-13 at 15:28 -0400, jim owens wrote: > Joe Peterson wrote: > > 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. > > I'm a filesystem guy so I only use ones I know do what I want, > I never trust ones I don't know about :) > > I agree with you about the danger of assuming what a filesystem > will or won't do on local copies. I also fear that 99% of normal > users have an expectation that making a copy makes a new physical > instance (which of course is not safe if the device crashes either). > > I hate dealing with customers that have lost their data because > of the filesystem. > > > Morey Roof wrote: > > I was hoping to have it specified as a set of mount options or defaults > > controlled in the super block so that if you want to use it you can > > otherwise it doesn't exist. > > I don't have veto power in btrfs so my aversion means nothing. > > As you say, there are a number of good ways to control it. > > If you pursue this, I might suggest having a dedup limit > so they can say "keep at least 2 copies" or "just one". > > jim This is an interesting idea. Perhaps we could tie this in a little closer to the protection systems in btrfs so that depending on the type of protection chosen the dedup will try to match it. However, I need to start figuring out a prototype for this which is what I started this thread for. -Morey -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
