rsync compares all files again and again

Frank Steiner fsteiner-mail1 at
Fri Oct 14 03:13:24 MDT 2011


we do a 1:1 backup from our main raid to a backup raid every night with

rsync -a --delete /mnt/raid1/ /mnt/raid2

rsync is 3.09, filesystems are ext3, OS is SLES 11 SP1.

The rsync process takes several hours, even if no file has changed at all.
Using -vv I see that rsync compares all files every time and that takes
long for some hundreds of millions of small files.

Can I tell rsync it should not compare files in a directory if the 
directory has not changed, i.e., ctime is the same in source and target?

I.e., when I have a dir x with a subdir y and a file y1 in it, I see:

rsync -avv x z
created directory z
delta-transmission disabled for local transfer or --whole-file

on the first run and

rsync -avv x z
x/y/y1 is uptodate

on every following run. Why does rsync compare y1 again? 

I couldn't find a solution in the mailing list or FAQ and when googling.
I found a mail in this list telling that -a was the culprit and one
should add -O to fix it, but it doesn't make any difference.


Dipl.-Inform. Frank Steiner   Web:
Lehrstuhl f. Bioinformatik    Mail:
LMU, Amalienstr. 17           Phone: +49 89 2180-4049
80333 Muenchen, Germany       Fax:   +49 89 2180-99-4049
* Rekursion kann man erst verstehen, wenn man Rekursion verstanden hat. *

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