I don't get --link-dest, at all

Mac User FR macuserfr at free.fr
Tue Aug 11 15:55:55 MDT 2009


I think your problem is with reading the correct size of folders as  
there have hard links. To do this with du command, try:
du -sh /home/backup/*

As far as I know, du command will only report the "real" disk size if  
the 2 hard links are in the du "scoop". Otherwise, running 2 times du  
on the 2 separate directories (wich have hardlinked files from one to  
the other into them) will show the size of those directories, counting  
the hardlinked as it's normal size.

Am I clear enough?

Hardlinked files are actually one unique file viewed from different  
places. If you look at each place at once they will show you the  
entire file size. To see different sizes you need to see both places  
at same time with a command that handle hardlinks (as du does).

 From man du:
"Files having multiple hard links are counted (and displayed) a single  
time per du execution."

Mind the "du execution", so you have to have both directories on the  
same command :)

Best regards,

Vitorio

Le 11 août 09 à 23:25, Scott Schappell a écrit :

> Hourly I have an rsync job backup /home to /home/backup.  I have 24  
> directories (one for each hour):
>
> home.0
> ...
> home.23
>
> Here is the script I am running via cron:
>
> #! /usr/local/bin/bash
> dest=`date +%k | sed 's/ //g'`
> linkdir=`date -v-1H +%k | sed 's/ //g'`
> chflags -R noschg /home/backup
> rm -rf /home/backup/home.$dest
> rsync -ahHP --numeric-ids --delete --stats --link-dest=../ 
> home."$linkdir"\
>      --exclude=/backup/* /home/ /home/backup/home."$dest"/ > /var/ 
> rsync.log
> sleep 2
> chflags -R schg /home/backup
>
> Per reading this list and other google finds, it was stated that for  
> link-dest to work, the destination must be empty, which I do.   
> However, let's say a 2PM backup runs.  The 2PM backup has 2.7GiB  
> (the current size of /home).  The 1PM backup directory is also 2.7GiB.
>
> [root at arthur /home/backup/home.14]# du -hcd0
> 2.7G    .
> 2.7G    total
> [root at arthur /home/backup/home.14]#
>
> [root at arthur /home/backup/home.13]# !du
> du -hcd0
> 2.7G    .
> 2.7G    total
> [root at arthur /home/backup/home.13]#
>
> For a specific file:
>
> [root at arthur /home/backup/home.14/archon/public_html]# ls -li d2x.jpg
> 22963255 -rwxr-xr-x  2 archon  archon  47318 Oct 29  2008 d2x.jpg
> [root at arthur /home/backup/home.14/archon/public_html]#
>
> [root at arthur /home/backup/home.13/archon/public_html]# !ls
> ls -li d2x.jpg
> 22963255 -rwxr-xr-x  2 archon  archon  47318 Oct 29  2008 d2x.jpg
> [root at arthur /home/backup/home.13/archon/public_html]#
>
> Both files share the same inode number, so I'm assuming it's a  
> hardlink, but why is the home.14 directory still saying 2.7GiB used?  
> Shouldn't it only be using whatever the delta is between home.13 and  
> home.14 (in this case, rsync reported copying over about 40 MiB of  
> data).
>
> df -h shows that /home is 8.6GiB when only ~3 GiB is actually being  
> used, so it's still creating fresh copies.
>
> I'm guessing I'm misunderstanding what --link-dest does, as I  
> understood it to create a hardlink to the file in the link-dest  
> directory if the file does not exist in the destination directory.
>
> Here's a log from the 2PM script run:
>
> [root at arthur /var]# cat rsync.log
> sending incremental file list
> created directory /home/backup/home.14
> archon/IMAPdir/Apple Mail To Do/
> archon/IMAPdir/Deleted Messages/
> archon/IMAPdir/Deleted Messages/bincimap-cache
>       2.22K 100%    0.00kB/s    0:00:00 (xfer#1, to-check=1943/2336)
> archon/IMAPdir/Deleted Messages/bincimap-uidvalidity
>          75 100%    0.60kB/s    0:00:00 (xfer#2, to-check=1942/2336)
> archon/IMAPdir/Deleted Messages/cur/
> archon/IMAPdir/Deleted Messages/cur/ 
> 1250024242.R2110010672M559524P93911Q41.arthur.silvertree.org:2,S
>      24.44K 100%  194.07kB/s    0:00:00 (xfer#3, to-check=1921/2336)
> archon/IMAPdir/Deleted Messages/new/
> archon/IMAPdir/Deleted Messages/tmp/
> archon/IMAPdir/Freecycle/
> archon/IMAPdir/Freecycle/bincimap-cache
>         876 100%    6.96kB/s    0:00:00 (xfer#4, to-check=1890/2336)
> archon/IMAPdir/Freecycle/bincimap-uidvalidity
>          74 100%    0.59kB/s    0:00:00 (xfer#5, to-check=1889/2336)
> archon/IMAPdir/Freecycle/cur/
> archon/IMAPdir/Freecycle/cur/ 
> 1250023358.R784558821M677376P93911Q39.arthur.silvertree.org:2,
>       5.20K 100%   40.95kB/s    0:00:00 (xfer#6, to-check=1879/2336)
> archon/IMAPdir/Freecycle/new/
> archon/IMAPdir/Freecycle/tmp/
> archon/Maildir/
> archon/Maildir/bincimap-cache
>       1.13K 100%    2.14kB/s    0:00:00 (xfer#7, to-check=1041/3870)
> archon/Maildir/bincimap-uidvalidity
>          75 100%    0.14kB/s    0:00:00 (xfer#8, to-check=1040/3870)
> archon/Maildir/cur/
> archon/Maildir/cur/1250021559.7658.arthur.silvertree.org:2,S
>       7.60K 100%   13.45kB/s    0:00:00 (xfer#9, to-check=1026/3870)
> archon/Maildir/cur/1250022468.8904.arthur.silvertree.org:2,S
>       7.76K 100%   13.71kB/s    0:00:00 (xfer#10, to-check=1025/3870)
> archon/Maildir/cur/1250022542.9042.arthur.silvertree.org:2,ST =>  
> archon/IMAPdir/Deleted Messages/cur/ 
> 1250024242.R2110010672M559524P93911Q41.arthur.silvertree.org:2,S
> archon/Maildir/cur/1250023069.9684.arthur.silvertree.org:2,ST =>  
> archon/IMAPdir/Freecycle/cur/ 
> 1250023358.R784558821M677376P93911Q39.arthur.silvertree.org:2,
> archon/Maildir/cur/1250023397.10077.arthur.silvertree.org:2,S
>       4.68K 100%    8.26kB/s    0:00:00 (xfer#11, to-check=1022/3870)
> archon/Maildir/cur/1250023861.10654.arthur.silvertree.org:2,S
>       6.45K 100%   11.38kB/s    0:00:00 (xfer#12, to-check=1021/3870)
> archon/Maildir/new/
> archon/Maildir/tmp/
> backup/
> pinnacle/IMAPdir/Apple Mail To Do/
> romany/Maildir/new/
> romany/Maildir/new/1250023382.10044.arthur.silvertree.org
>       2.49K 100%    0.00kB/s    0:00:00 (xfer#13, to-check=1001/22172)
> romany/Maildir/tmp/
> scott.schappell/IMAPdir/Apple Mail To Do/
> scott.schappell/Maildir/
> scott.schappell/Maildir/bincimap-cache
>      46.29K 100%  279.03kB/s    0:00:00 (xfer#14, to-check=1004/24511)
> scott.schappell/Maildir/bincimap-uidvalidity
>          75 100%    0.30kB/s    0:00:00 (xfer#15, to-check=1003/24511)
> scott.schappell/Maildir/cur/
> scott.schappell/Maildir/cur/1250023996.10809.arthur.silvertree.org:2,
>      20.12K 100%   66.38kB/s    0:00:00 (xfer#16, to-check=1024/24943)
> scott.schappell/Maildir/new/
> scott.schappell/Maildir/tmp/
> soucon/3.1/game/data/sc.gdbm
>      34.97M 100%   16.10MB/s    0:00:02 (xfer#17, to-check=1014/28108)
>
> Number of files: 32052
> Number of files transferred: 17
> Total file size: 2.79G bytes
> Total transferred file size: 35.10M bytes
> Literal data: 35.10M bytes
> Matched data: 0 bytes
> File list size: 991.74K
> File list generation time: 0.009 seconds
> File list transfer time: 0.000 seconds
> Total bytes sent: 36.10M
> Total bytes received: 2.71K
>
> sent 36.10M bytes  received 2.71K bytes  4.81M bytes/sec
> total size is 2.79G  speedup is 77.36
>
> rsync version:
>
> [root at arthur /var]# rsync --version
> rsync  version 3.0.6  protocol version 30
> Copyright (C) 1996-2009 by Andrew Tridgell, Wayne Davison, and others.
> Web site: http://rsync.samba.org/
> Capabilities:
>    64-bit files, 32-bit inums, 32-bit timestamps, 64-bit long ints,
>    socketpairs, hardlinks, symlinks, IPv6, batchfiles, inplace,
>    append, ACLs, xattrs, no iconv, symtimes
>
> Installed from FreeBSD 7.2 ports collection.
>
> Thanks for any help in enabling me to understand how this works.
>
> Scott
>
>
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