I'm using tar to create backups. According to the documentation, listed-incremental mode should consider all NFS file systems as equal, but that doesn't work for me. If an NFS filesystem gets a new device number than last time, tar wants to rebackup the whole tree.
I took a look in the code, and if I understand it correctly, the heuristic is that if the most significant bit of the device number is set, then it is an NFS file system. On my Fedora Linux system, however, NFS file systems gets very low numbers, with the major number equal to zero and the minor number being around 20. (It appears to be the "next free number". But I haven't investigated in detail where it starts counting and if there are other conditions involved.) See an example of doing "stat" on my home directory on a machine where it is NFS mounted: freddi$ env LANG=C stat ~ File: `/home/g\303\266ran' Size: 12288 Blocks: 32 IO Block: 262144 directory Device: 13h/19d Inode: 3852847 Links: 146 Access: (2755/drwxr-sr-x) Uid: ( 503/ göran) Gid: ( 503/ göran) Access: 2009-02-03 11:04:16.000000000 +0100 Modify: 2009-02-03 10:39:51.000000000 +0100 Change: 2009-02-03 10:39:51.000000000 +0100
