Linux Shell Scripting Cookbook - Third Edition

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The hdparm command can test a disk's performance. The -t and -T options performs timing tests on buffered and cached reads, respectively:

# hdparm -t /dev/sda
Timing buffered disk reads: 486 MB in  3.00 seconds = 161.86 MB/sec

# hdparm -T /dev/sda
Timing cached reads:   26492 MB in  1.99 seconds = 13309.38 MB/sec