On Fri, 2006-02-10 at 15:53 +0100, Wiebe Cazemier wrote: > Ben, > > A while back I suggested a feature to include hash-checks to determine > if files have changed or not, instead of the mtimes+size combo. I trust > you remember. I've been away from the list a while, and I see there has > been a poll. I didn't see this feature in the poll, but I'd like to > emphasise that it is quite important. I've just discovered another > situation in which mtime+size is not reliable. I'll explain: > > if you have two files of equal size, but different contents, and copy > one over the other, the mtime of the target file is preserved. Now, > because the size and mtime haven't changed, rdiff-backup doesn't see it > as a change and doesn't back it up. This if course, would be very > undesirable. > > Here is an example of what I mean: > > ================================ > # lh > total 8.0K > -rw------- 1 [owner] users 16 Feb 10 15:46 a > -rw------- 1 [owner] users 16 Feb 10 15:47 b > > # cat a;cat b > this is a file. > this is b file. > > # cp a b > > # lh > total 8.0K > -rw------- 1 [owner] users 16 Feb 10 15:46 a > -rw------- 1 [owner] users 16 Feb 10 15:47 b > > # cat a;cat b > this is a file. > this is a file. > ================================
I did the same and mtime has changed for me: dd if=/dev/urandom of=a count=1 dd if=/dev/urandom of=b count=1 stat a b File: `a' Size: 512 Blocks: 8 IO Block: 131072 regular file Device: 806h/2054d Inode: 2094563 Links: 1 Access: (0664/-rw-rw-r--) Uid: ( 1001/kouzminv) Gid: ( 440/ vadiki) Access: 2006-02-10 11:49:56.000000000 -0500 Modify: 2006-02-10 11:49:56.000000000 -0500 Change: 2006-02-10 11:49:56.000000000 -0500 File: `b' Size: 512 Blocks: 8 IO Block: 131072 regular file Device: 806h/2054d Inode: 2094711 Links: 1 Access: (0664/-rw-rw-r--) Uid: ( 1001/kouzminv) Gid: ( 440/ vadiki) Access: 2006-02-10 11:50:01.000000000 -0500 Modify: 2006-02-10 11:50:01.000000000 -0500 Change: 2006-02-10 11:50:01.000000000 -0500 cp a b stat a b File: `a' Size: 512 Blocks: 8 IO Block: 131072 regular file Device: 806h/2054d Inode: 2094563 Links: 1 Access: (0664/-rw-rw-r--) Uid: ( 1001/kouzminv) Gid: ( 440/ vadiki) Access: 2006-02-10 11:51:20.000000000 -0500 Modify: 2006-02-10 11:49:56.000000000 -0500 Change: 2006-02-10 11:49:56.000000000 -0500 File: `b' Size: 512 Blocks: 8 IO Block: 131072 regular file Device: 806h/2054d Inode: 2094711 Links: 1 Access: (0664/-rw-rw-r--) Uid: ( 1001/kouzminv) Gid: ( 440/ vadiki) Access: 2006-02-10 11:50:01.000000000 -0500 Modify: 2006-02-10 11:51:20.000000000 -0500 Change: 2006-02-10 11:51:20.000000000 -0500 Notice *** Modify: 2006-02-10 11:51:20.000000000 -0500 *** I think you miss SECONDS in your lh listing. Looks like "b" was created 15:47 and then you copied a -> b at 15:47. Vadim > > I really think this feature should be part of the next stable release, > because now I can't fully trust my backup to be accurate. > > On a sidenote, the wiki at > http://rdiff-backup.solutionsfirst.com.au/?SuggestedFeatures doesnt seem > to work, the articles are not accessible. > > Regards, > > Wiebe Cazemier > _______________________________________________ > rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org > http://lists.nongnu.org/mailman/listinfo/rdiff-backup-users > Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki -- Vadim Kouzmine <[EMAIL PROTECTED]> _______________________________________________ rdiff-backup-users mailing list at rdiff-backup-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/rdiff-backup-users Wiki URL: http://rdiff-backup.solutionsfirst.com.au/index.php/RdiffBackupWiki
