Joerg Schilling wrote: > Matthew Ahrens <[EMAIL PROTECTED]> wrote: > >> Joerg Schilling wrote: >>> The best documented one is the inverted meta data tree that allows wofs to >>> write >>> only one new generation node for one modified file while ZFS needs to also >>> write new >>> nodes for all directories above the file including the root directory in >>> the fs. >> I believe you are thinking of indirect blocks, which are unrelated to the >> directory tree. In ZFS and most other filesystems, ancestor directories >> need >> not be modified when a file in a directory is modified. > > Isn't this against what I've read? > > If you write inode data to a different location than before, you need a way > to > tell the ancestor directory where the new data is located.
No; directories point to the files (and directories) that they contain by object (inode) number, not by block pointer (physical disk location). When new contents are written to a file, its object (inode) number does not change. > From what I've read so far and what I have in mind from a personal talk with > Jeff Bonwick in September 2004, this is done by rewriting at least parts of > the > ancestor directory inode. That is incorrect; you must have misunderstood Jeff. Could you point me to where you've read this, so that it can be corrected or clarified? --matt _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
