Network Monitoring

http://www.howtoforge.com/network_monitoring_with_ntop

rrdtool + cacti

use iostat:

iostat
Linux 2.6.18-92.1.6.el5 (yourhostname) 05/12/2009

avg-cpu: %user %nice %system %iowait %steal %idle
0.29 0.05 0.54 0.09 0.00 99.04

Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
sda 1.53 0.60 16.74 843702 23657360
sdb 0.06 0.40 1.77 571688 2496888
dm-0 0.02 0.08 0.12 117306 169328
dm-1 0.38 0.00 0.77 4902 1085280
dm-2 1.14 0.09 9.08 131618 12832832
dm-3 0.77 0.06 6.14 84162 8678000
dm-4 0.28 0.04 0.56 63482 791708
dm-5 0.02 0.28 0.07 394794 100160
dm-6 0.00 0.00 0.00 4040 0
dm-7 0.06 0.01 0.47 18098 663640
dm-8 0.18 0.38 1.30 535978 1833248