hard links (leafnode)

Thufir hawat.thufir at gmail.com
Sun Sep 23 07:52:39 UTC 2012

I'm backing up leafnode NNTP server contents as per:

"It is, however, important that tar, pax, cpio, or whichever tool you
use, is (A) capable of, and (B) instructed to save and restore
hard links as hard links (rather than just copies). Each article has
only one file (inode, technically speaking) with multiple names (= hard
links). This makes sure that we do not waste space (inodes and blocks)
on the file systems while maintaining fast access both by article number
and by message ID."


and am wondering about hard links.  I'm using ext4:

root at dur:~# df -T
Filesystem           Type     1K-blocks     Used Available Use% Mounted on
/dev/mapper/dur-root ext4      27637336 18809728   7442136  72% /
udev                 devtmpfs   1006672        4   1006668   1% /dev
tmpfs                tmpfs       405680      840    404840   1% /run
none                 tmpfs         5120        4      5116   1% /run/lock
none                 tmpfs      1014192      396   1013796   1% /run/shm
cgroup               tmpfs      1014192        0   1014192   0% /sys/fs/
/dev/sdb1            ext2        233191    48285    172465  22% /boot
root at dur:~# 

I'll be using DAR, <dar.linux.free.fr>, and it looks like DAR should 
handle hard links fine:


hard links are properly saved in any case and properly restored if 
possible. For example, if restoring across a mounted file system, hard 
linking will fail, but dar will then duplicate the inode and file 
contents, issuing a warning. Hard link support includes the following 
inode types: plain files, char devices, block devices, symlinks (Yes, you 
can hard link symbolic links! Thanks to Wesley Leggette for the info ;-) 


Just want to make sure before I do the backup. It should be fine?  Just 
backup, and then I can put it back onto the spool at /var/news?



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