rsync - Feb 2004 - Speed up rsync ,cwRsync and replay changes against a file

Hi guys,

I recently installed and setup cwRsync on a Windows 2000 Server -
http://www.itefix.no/cwrsync/ -, and I was very impressed. I just
followed the instructions on the website and got it working. 

I am using it to mirror 30Gb's of mailboxes everynight (only grabbing
the changes to each file), from a Windows 2000 box to a Linux box (RH9).

The nightly replication takes approximately 8 hrs to complete, but the
actual size of the mailbox directory only increases by about 120Mb a
day. There are 750 mailboxes and each mailbox is between 50 and 200Mb in
size.

I am using the following command line options:

rsync -avz hostname::MailBoxes /mailboxreplica

Can anyone recommend ways to speed this up - is there some extra
compression I can use, or a kind of "quick checksum" option that I
could
use?

I was also wondering if there is a way to capture what rsync sees as the
changes to a file, and then replay them against a file at a later date,
as this would be useful as an incremental backup/restore option.

In general think rsync rocks and I am very impressed by it's reliability
and flexiblity!

Reuben
reuben@presence-systems.com

> I recently installed and setup cwRsync on a Windows 2000 Server -
> http://www.itefix.no/cwrsync/ -, and I was very impressed. I just
> followed the instructions on the website and got it working.=20
> 
> I am using it to mirror 30Gb's of mailboxes everynight (only grabbing
> the changes to each file), from a Windows 2000 box to a Linux box (RH9).
> 
> The nightly replication takes approximately 8 hrs to complete, but the
> actual size of the mailbox directory only increases by about 120Mb a
> day. There are 750 mailboxes and each mailbox is between 50 and 200Mb in
> size.
> 
> I am using the following command line options:
> 
> rsync -avz hostname::MailBoxes /mailboxreplica
> 
> Can anyone recommend ways to speed this up - is there some extra
> compression I can use, or a kind of "quick checksum" option that
I could
> use?
If you are on a fast network, -z will probably slow you down.

Rsync + cygwin is typically slow due to the system call overhead in
cygwin.  There is a performance patch (patches/craigb-perf.diff)
included with the 2.5.6, 2.5.7 and 2.6.0 releases that makes a
measurable improvement.  This patch is now in CVS.

So you should build rsync from releases sources after applying the
patches/craigb-perf.diff patch (or build from CVS).  Or you can try a
pre-built executable with the patch, like the cygwin-rsyncd package
at http://backuppc.sourceforge.net.

Craig