DMA problem

[jnojr]

DVD Shrink got very slow on me. A little searching around led me to the answer about uninstalling the IDE controllers, so I did that. It worked at full speed again... once. Since then, nothing helps. Shrink takes twice as long to create an ISO and uses 100% CPU. This certainly seems like a problem with DMA not working right. But how do I know? I'm looking for some kind of utility that will actually check and see if or how DMA is working. So far, all I get is a lot of "It should work, uninstall and try again". How do I get an absolute, definitive answer?

[guns1inger]

There is no definative answer. Windows drops out of DMA mode as a failsafe when repeated errors are detected ont he device. If it is a HDD then you may have imminent failure, or you may have a problem with an IDE cable. If it is an optical drive, it might be that the bios isn't always detecting it correctly at boot up. I have a gigabyte MB that doesn't always see the drive on the first boot. It will list all the HDDs without a problem, but the optical drive shows up as None about 50% of the time. If I then log into windows, the drive will be in PIO mode and run at 2x or slower. If, at the welcome screen, I elect to Turn Off Computer -> Restart, the bios will detect the drive, and windows will use DMA Mode 2. I have replaced cables, updated the bios on the MB and the firmware of the drive, all to no avail.

Dell does have a utility called PIOtoDMA which can force devices on the second IDE channel to use DMA Mode 2 without the need to reboot. Seems to work OK.

DMA should not affect CPU usage too much. I would expect to see shrink using close to 100% regardless, as it has a lot to do. Writing the ISO would certainly be a lot slower.

I would start by

1. Confirm that it is your HDDs that are running in PIO mode. If they are not, then that isn't the cause of your Shrink problem. I have never had performance problems from the optical drive being in PIO mode, except for read and write speed to that drive.

2. If your HDDs are dropping into PIO mode, run a scandisk to surface scan disk for problems, check that all IDE cables are seated properly, and consider replacing the cables on the drives that are acting up.

3. Upgrade your MB bios and consider putting the drive setting into bios if you are currently using auto-detect

[jnojr]

I would start by

1. Confirm that it is your HDDs that are running in PIO mode.

How?

[guns1inger]

Right-click on My Computer and select Manage from the menu. Click on Device Manager, then expand the IDE ATA/ATAPI Controllers branch in the right-hand pane. There should be a Primary and a Secondary. Double-click on each in turn, then click on the Advanced Settings tab. Both devices should have a Transfer Mode of "DMA is available". For connected devices, the Current Transfer Mode should be Ultra DMA Mode n, where n is device dependent. Most modern HDDs will be Mode 5, your optical devices will Mode 2. Do this for both the Primary and the Secondary IDE channels. If any of the devices are set to PIO mode you have a problem.