[svlug] FW: Hard disk optimizations

Dagmar d'Surreal dagmar at dsurreal.org
Sun Mar 11 14:58:01 PST 2001


On Sun, 11 Mar 2001, Daevid Vincent wrote:

> I just tried this myself and thought it might be of interest to others on
> this list.
> 
> #> /sbin/hdparm -d1 -m16 -X66 /dev/hda
> 
> /dev/hda:
>  setting multcount to 16
>  setting using_dma to 1 (on)
>  setting xfermode to 66 (UltraDMA mode2)
>  multcount    = 16 (on)
>  using_dma    =  1 (on)
> 
> -----Original Message-----
> From: lugor-announce-admin at xcski.com
> [mailto:lugor-announce-admin at xcski.com]On Behalf Of Jim Campbell
> Sent: Sunday, March 11, 2001 9:11 AM
> To: lugor-announce at xcski.com
> Subject: [LUGOR] Hard disk optimizations
> 
> 
> Hi,
> This may already be known to many of you, but I read a hint that you could
> optimize hard disk performance on modern PC systems with IDE drives by
> activating DMA, enabling multi-sector I/O, and using Ultra DMA mode 2
> transfers .  RedHat Linux doesn't attempt to do this, in the name of
> portability.
> 
> When I tried the hint, which is to run:
> 
> /sbin/hdparm -d1 -m16 -X66 /dev/hda
> 
> My hard disk performace when from 3 MB per second to over 9 MB per second.
> The system performance and user experience is noticeably better.  (Linux is
> already faster than Windows 98 on the same disk - with this optimization, it
> feels like I am going at warp speed. :) )
> 
> Does anyone else do this?  If so, any other pointers or suggestions?

The reason no one's distribution does this by default is very simple.  It
requires support for your particular chipset in the kernel for this to
function properly, and without it, the settings don't do anything but look
cool.  The hdparm command only tells the drive to _try_ using the UDMA and
PIO modes, but doesn't do anything about the controller.

The other really fun reason why it's not done by default is if the kernel
support for your controller flakes out (which is still quite
possible) you'll be looking at a completely mangled filesystem.

Read the man pages on hdparm, and do some of the happy little
benchmarks.  You're likely to find that you can turn these features on
with no problem, but you'll still be operating at the normal drive speeds.





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