reducing I/O and system load

[Denis Solovyov]

>> 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?
PL> I noticed this option in the man page which might be of help:
PL>      --bwlimit=KBPS          limit I/O bandwidth; KBytes per second

I tried --bwlimit, it seems that it works for local transfers as well as
for  network,  but  it  doesn't  help me much. Also, it is impossible to
predict how many files should be transferred, so with --bwlimit transfer 
could take too much time (if there are many updated files)...

Best regards,
Denis Solovyov