rsync - Jun 2010 - Backup to NTFS USB drive --compare-dest not working

When I'm running "rsync --compare-dest" on a local Linux volume
(ext4) it
works as expected (duplicate files not created) however when same commands
with same options are run on NTFS USB drive (in my scenario below mounted to
/share/external/sdt5) all the files are copied regardless if they have been
updated or not. I have spent many hours trying to figure out what could be
wrong and trying different options, still I have no idea how to make it
work. I will appreciate any help.

I have set up following directories for my test:
SourceDir/
FullBackupDir/
IncBackupDir/
NtfsFullBackupDir -> /share/USBDisk2/TMP/NtfsFullBackupDir/
NtfsIncBackupDir -> /share/USBDisk2/TMP/NtfsIncBackupDir/

Following commands work as expected, the files are copied from the source
directory only to the "full backup" directories and not to the
"inc backup"
directories:
[~/test] # rsync -avh --delete SourceDir/ FullBackupDir/
[~/test] # rsync -avh --compare-dest=/root/test/FullBackupDir SourceDir/
IncBackupDir/

But for some reason following commands have different results: nothing is
copied to IncBackupDir (absolutely correct behaviour!) however all files are
copied from SourceDir to NtfsIncBackupDir again - why?
[~/test] # rsync -avh --compare-dest=/root/test/FullBackupDir SourceDir/
IncBackupDir/
[~/test] # rsync -avh --compare-dest=/root/test/NtfsFullBackupDir SourceDir/
NtfsIncBackupDir/


Complete log is below:

[~/test] # rsync -avh --delete SourceDir/ FullBackupDir/
sending incremental file list
./
1.txt
2.txt

sent 171 bytes  received 53 bytes  448.00 bytes/sec
total size is 6  speedup is 0.03

[~/test] # rsync -avh --compare-dest=/root/test/FullBackupDir SourceDir/
IncBackupDir/
sending incremental file list
./

sent 79 bytes  received 15 bytes  188.00 bytes/sec
total size is 6  speedup is 0.06

[~/test] # rsync -avh --delete SourceDir/ NtfsFullBackupDir/
sending incremental file list
./
1.txt
2.txt

sent 171 bytes  received 53 bytes  89.60 bytes/sec
total size is 6  speedup is 0.03

[~/test] # rsync -avh --compare-dest=/root/test/NtfsFullBackupDir SourceDir/
NtfsIncBackupDir/
sending incremental file list
./
1.txt
2.txt

sent 85 bytes  received 21 bytes  212.00 bytes/sec
total size is 6  speedup is 0.06
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On Fri, 2010-06-04 at 01:03 +0100, Sergey Shatokhin
wrote:
> When I'm running "rsync --compare-dest" on a local Linux
volume (ext4)
> it works as expected (duplicate files not created) however when same
> commands with same options are run on NTFS USB drive (in my scenario
> below mounted to /share/external/sdt5) all the files are copied
> regardless if they have been updated or not.
	hi,
Normally, the -a option can be used to perfectly mirror the files.
However, if the target filesystem does not support permissions, a
different set of options should be used to avoid warnings from rsync. To
synchronize data to a USB drive with a FAT filesystem, I use the -rlt
options.
	bye,
	nomnex

> if the target filesystem does not support permissions, a
> different set of options should be used to avoid warnings from rsync. To
> synchronize data to a USB drive with a FAT filesystem, I use the -rlt
> options.
Thanks nomnex, you're absolutely right!
As soon as I changed -a to -rlt everything began working as expected! It
must have been -pgo options that are a part of -a that gave me such
problems.

Thanks again, I didn't expect someone would be able to help me resolve it so
quickly!
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