reducing I/O and system load

[Denis Solovyov]

This  is  probably  the  most eternal question concerning rsync, but I'm
really  in  doubt  since I can't find the appropriate answer or solution
anywhere for many months.

I'm using rsync for simple daily back up data from one HD to another. It
takes  about  10  minutes  daily  under  "nice  -n  19".  The problem is
well-known  as  I  see  -  several other services such as httpd or mysql
begin responding slowly  (up  to  10 sec for mysql queries which usually
processed in a small fraction of a second).

The  reason  is  pretty  obvious,   but  still  are  there  any  general
recommendations on how to solve or appreciably soften the situation?

Best regards,
Denis Solovyov