[Ham-Computers] RE: Drive DMA Mode versus PIO?

[Hsu, Aaron (NBC Universal)]

Phil,

Don't change the DMA mode in the BIOS...it should be set to "AUTO" and the BIOS will negotiate the appropriate mode at boot.  Also, Windows XP will reset this mode (and re-negotiate with the drive) as soon as the native 32-bit drivers are loaded.

What you should check are the "Primary IDE" and "Secondary IDE" channels in Windows' Device Manager.  Under the "Advanced Settings" tab, you'll find the "Transfer mode" setting - it should be set to "DMA if available".  WinXP and Win2K defaulted CD-ROM drives to "PIO".  WinXP SP1 and SP2 changed the optical drive default to "DMA".  If you upgraded to SP1 (or SP2) from base XP, then it's possible the mode carried over.  Just make the change to "DMA" and you're set.  The only problem is if the CD-ROM drive is really old...the first CD-ROM drives that supported DMA weren't stable in DMA mode.  That's why earlier versions of Windows defaulted to PIO mode for optical drives.

As mentioned above, Win2K and original WinXP defaulted to "PIO", so if anyone's running either of these and don't know about this setting, now's the time to check.

NOTE:  There are times when WinXP will "downgrade" a drive's mode to a lower level due to errors detected on the IDE channel.  In this case, the mode still shows as "DMA", but if you run a drive benchmark (such as HDTach), you'll be getting PIO speeds, typically under 5MB per second.  If you check the event log, you'll notice that at some point, a disk error was logged and that was probably when Windows lowered the performance to mitigate the issue.  Problem is, it downgrades, but never upgrades the mode back to full performance.

I ran into this issue with one of my systems earlier this month.  Digging high and low, I finally found an article on how to reset the performance counter/checksum that Windows keeps that limits the PIO/DMA mode.  If anyone wants this info, I'll see if I can find the link again...it involves modifying the registry.

73,

  - Aaron Hsu, NN6O


p.s. One last suggestion...download and install the latest chipset support update for your chipset (Intel).

-----Original Message-----
Sent: Monday, September 25, 2006 3:19 PM
Subject: [Ham-Computers] Drive DMA Mode versus PIO?

Hi All,

Today I loaded some Guitar recording software (RIFFWORKS by Line 6) on my computer to try out.  It's basically a complete "Software recording studio" 
and operates in conjuction with my Guitar "Pedalboard" which is connected by a USB cable.  Before the software loaded it ran a full system scan to determine if the system was properly configured to run it (it doesn't make any system changes on it's own).

It detected only one problem, then proceeded to allow me to install the software.  The failure reads as follows.
"FAILED      Drive DMA Mode (   0): PIO detected on SONY CD-ROM CDU5212", 
this is my "secondary" CD drive.

QUESTION:  If I recall correctly, I can change this in the bios setup routine when the computer starts up.  HOWEVER, will there be any NEGATIVE aspects to changing this drive to DMA?  And what DMA mode do I want to set up for?

Here is the COMPLETE printout of the report that was generated in case somebody needs more information to make a valid suggestions.

*** snip ***

73 de Phil,  KO6BB
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