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Date: Tue, 24 Mar 2009 11:16:55 +0800
From: KHMan <keinhong AT gmail DOT com>
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To: cygwin AT cygwin DOT com
Subject: Re: rsync under cygwin too slow
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Alfred von Campe wrote:
>> rsync -rtuplg --stats --verbose --progress --modify-window=2 
>> /cygdrive/c/localfolder /cygdrive/z/backups/
>> ...
>> ...
>> The local and remote folders were already synchronized, that is why 0 
>> files were transferred. File list generation did take only 3 minutes 
>> but the whole process took more than 1.5 hours to finish and consumed 
>> a whopping 1.9 GB of downloaded bytes and 0.4 GB of uploaded bytes as 
>> per network counters. For what? Zero files, Zero bytes of file data.
> 
> I'm pretty sure this is because rsync has to copy all the files locally 
> to compare them to see if they need to be copied.  Try running the rsync 
> as a service on the system that hosts the Z: drive (or run rsync over 
> ssh to the system that hosts the Z drive) and you will see large 
> performance improvement.

Looks to me there is no --checksum option, so rsync skips based on 
size and modtime. I do something similar to Vinod. Here is an 
extra data point to compare against (y and u are on separate 
drives on same machine):

$ time rsync -a --progress --stats --delete /cygdrive/y/Installs/ 
/cygdrive/u/Installs/
sending incremental file list

Number of files: 284
Number of files transferred: 0
Total file size: 2284961277 bytes
Total transferred file size: 0 bytes
Literal data: 0 bytes
Matched data: 0 bytes
File list size: 8583
File list generation time: 0.030 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 8606
Total bytes received: 22

sent 8606 bytes  received 22 bytes  17256.00 bytes/sec
total size is 2284961277  speedup is 264830.93

real    0m0.678s
user    0m0.155s
sys     0m0.217s

With --checksum:

$ time rsync -ac --progress --stats --delete /cygdrive/y/Installs/ 
/cygdrive/u/Installs/
sending incremental file list

Number of files: 284
Number of files transferred: 0
Total file size: 2284961277 bytes
Total transferred file size: 0 bytes
Literal data: 0 bytes
Matched data: 0 bytes
File list size: 12951
File list generation time: 5.476 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 12974
Total bytes received: 22

sent 12974 bytes  received 22 bytes  234.16 bytes/sec
total size is 2284961277  speedup is 175820.35

real    0m55.964s
user    0m23.388s
sys     0m7.202s

> [snip snip]

-- 
Cheers,
Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia

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