# date ; dd bs=1M count=1000 if=/dev/zero of=hugefile.dat ; date
 Thu Nov  3 00:10:01 CST 2005
 1000+0 records in
 1000+0 records out
 Thu Nov  3 00:11:04 CST 2005
 # date ; dd bs=1M count=1000 of=/dev/null if=hugefile.dat ; date
 Thu Nov  3 00:11:08 CST 2005
 1000+0 records in
 1000+0 records out
 Thu Nov  3 00:11:41 CST 2005
 # hdparm -tT /dev/hda

 /dev/hda:
  Timing buffer-cache reads:   128 MB in  2.59 seconds = 49.42 MB/sec
  Timing buffered disk reads:  64 MB in  2.52 seconds = 25.40 MB/sec
 Hmm.. suspicious results: probably not enough free memory for a proper test.
 # hdparm -Tt /dev/sda1

 /dev/sda1:
  Timing buffer-cache reads:   128 MB in  3.20 seconds = 40.00 MB/sec
  Timing buffered disk reads:  64 MB in  9.56 seconds =  6.69 MB/sec