when server start backups apache down

hi
plz help me

when server start backups apache down and server is very load
and all web sites down

this is top command


03:55:51 up 20:54, 1 user, load average: 34.04, 33.69, 17.33
450 processes: 446 sleeping, 2 running, 2 zombie, 0 stopped
CPU states: 4.7% user 3.3% system 0.0% nice 0.0% iowait 91.8% idle
Mem: 1022792k av, 1014244k used, 8548k free, 0k shrd, 36528k buff
659872k actv, 141980k in_d, 22120k in_c
Swap: 20972848k av, 245640k used, 20727208k free 384580k cached

Does apache say anything in it's logs?

/var/log/httpd/error_log
/var/log/messages

Which backup method are you referring to?

John