How to monitor performance

disk

$ hdparm -Tt /dev/hda
/dev/hda:
Timing cached reads:   1468 MB in  2.00 seconds = 733.01 MB/sec
Timing buffered disk reads:  120 MB in  3.04 seconds =  39.41 MB/sec

for SMART-enabled disks

smartctl -a /dev/hda

Memory

$ free -m (in MB)

           total       used       free     shared    buffers     cached
Mem:           503        375        128          0         55        240
-/+ buffers/cache:         79        424
Swap:         1023          0       1023

Real-time monitoring

Use the top and atop commands.

Historical monitoring

Use the sar package.