Rsync performance with large exchange database files

[bruce at sqls.net]

I'm using a mixture of FreeBSD w/ ZFS+snapshots and rsync to backup all 
the servers at my day job. This works pretty good overall but on one 
server it's not working so well :)

We have an Exchange 2003 server with 4 separate mail store databases. 
One of them is roughly 900GB the others are ~200GB, ~160GB, and ~50GB. 
Rsync seems to spend a lot of time trying to find the differences in the 
files. On the Windows server where rsync is kicked off there's very 
little CPU or RAM usage for the rsync client. On the server rsync 
(rsyncd, no ssh) is using around 70-85% of a cpu (well, half a cpu due 
to hyper threading). I'm using VSS on the windows server to take a 
snapshot and expose it then running rsync from that to avoid locking 
issues.

Is there anything I should check to help narrow down "problems?" or any 
settings I should try that could help speed things up any?

Below is the final output of the last two rsync runs to give you an 
idea. It's taking 30-40+ hours to finish even though it's only 
transferring 80-160GB of change. Right now I'm testing this against a 
local rsync server so it should get pretty fast network performance. 
Eventually it will be moved to our off-site backup but that connection 
is still pretty fast (20 MBbit) and the backup is only hitting 800-1000 
Kbytes/sec.


Number of files: 19
Number of files transferred: 6
Total file size: 1265.74G bytes
Total transferred file size: 1057.06G bytes
Literal data: 160.67G bytes
Matched data: 896.39G bytes
File list size: 482
File list generation time: 0.001 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 160.71G
Total bytes received: 73.74M

sent 160.71G bytes received 73.74M bytes 991.84K bytes/sec
total size is 1265.74G speedup is 7.87
[sender] _exit_cleanup(code=0, 
file=/home/lapo/package/rsync-3.0.9-1/src/rsync-3.0.9/main.c, 
line=1052): about to call exit(0)

real 2833m1.324s
user 2225m55.906s
sys 45m10.015s

Number of files: 11
Number of files transferred: 6
Total file size: 1268.78G bytes
Total transferred file size: 1251.04G bytes
Literal data: 83.43G bytes
Matched data: 1167.61G bytes
File list size: 216
File list generation time: 1.360 seconds
File list transfer time: 0.000 seconds
Total bytes sent: 83.48G
Total bytes received: 87.25M

sent 83.48G bytes received 87.25M bytes 836.85K bytes/sec
total size is 1268.78G speedup is 15.18

real 1745m5.647s
user 1129m14.000s
sys 39m58.875s

Thanks (in advance) for the help :)
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