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HDPARM


The command ¨hdparm¨ is for showing and tweaking your harddisk performance.

To see how your harddisk does compare:

CODE
$ su
< password >
# hdparm -tT /dev/hda

( or hdb )

Will give you a result like:

/dev/hda:
Timing buffer-cache reads: 128 MB in 0.68 seconds =188.24 MB/sec
Timing buffered disk reads: 64 MB in 1.59 seconds = 40.25 MB/sec


Now before you start tweaking, a warning is on its place, some tweaks may even make your HD unstable, so before starting to change settings:

CODE
$ su
< password >
# hdparm /dev/hda


And note down the numbers so you can set them back to the old values if needed !

And read O´Reilly attentively !!

To find additional info about your HD:

CODE
# hdparm -i /dev/hda


This will show you what are the possible settings for your harddisk.

An example:
To set 32-bit I/O support flag to 3
multicount to 16
DMA to 1 ( = on )

You give the following command: ( as root )

CODE
# hdparm -c3 -m16 -d1 /dev/hda


Again: enabling DMA can in some cases lead to serious instability, so if needed:

CODE
# hdparm -d0 /dev/hda  

( will disable DMA )


After tweaking you run

CODE
# hdparm -tT /dev/hda


again and see if there is an increase of performance.


Have fun tweaking, ( or with the words of O´Reilly: Happy hacking ! ) but please, please be careful !


Bruno


PS: Additional info: axljab.homelinux.org


-- Jul 8 2003 ( Revised Nov 20 2006 ) --


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