meaning of "-T" option?

  • ktyang

    ktyang - 2009-02-16

    I know "hdparm -t" is used to test real hard speed. But I wonder "hdparm -T" is used for?
    If "-T" option is related to SATA II, as I know, the real speed of SATA II should be under 300MB/sec.
    Run "hdparm -T" on my PC. (OS: Ubuntu 8.10)
    I got "Timing cached reads:   2076 MB in  2.00 seconds = 1037.96 MB/sec".
    The speed is much over 300 MB/sec.

    The same test on win32 version (OS:Vista 32)
    I got 213.04MB/sec.

    These two different results make me confused. (Both tested with the same hardware)
    Does "hdparm -T" test hard disk interface?
    If yes, why the speed over 300MB/sec (SATA II spec)?

    my hard disk WD WD2500AAKS


    • John M. Drescher

      It times cached reads. Basically this tests your system cache speed / memory performance instead of your disk speed.


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