Slow Read Times?

Drew

Drew

E.M.I.
Anyone know what might cause windows to read a hard drive at really slow speeds (3.5 mbs)? Linux was reading the drive at normal speed, but Windows XP Pro was reading the drive very slowly. All that was done to it was to changes cases. No other systems were affected just the hard drive and there were no bad sectors reported on the disc.

The porblem has since been resolved and i have a fresh WIN XP install now but i was just wondering if anyone had any thoguths on what might have caused the problem. Maybe i can prevent it from happening again.
 
Drew

Drew

E.M.I.
How did that happen?

Is that a common thing to have it switch modes like that? I have had friends change cases and that never happened to them. I can't understand how the OS could be affected while everything was powered down and in peices. Any idea on how it might randomly changes modes liek that?
 
madmat

madmat

Soup Nazi
I forget the techincal reasons behind it but it happens when there's a reading error. The device manager will shift a drive that has a specific read error to PIO mode and it can be a royal pain in the neck to switch it back, it usually requires the fix you implemented which is a wipe/reload.
 
Drew

Drew

E.M.I.
That makes me feel better

I am glad that i at least went about fixing it properly. I tried and tried to find a fix for it but the wipe/re-load was the last option. I hate having to do all that work for nothing. I am relieved to hear this fix was (basically) my last option.

Thanks guys
 
Z

zachig

Obliviot
Here ya go ;) :

The programmed input/output (PIO) interface was the original method used to transfer data between the CPU (through the ATA controller) and an ATA device. The PIO interface is grouped into different modes that correspond to different transfer rates. The electrical signalling among the different modes is similar -- only the cycle time between transactions is reduced in order to achieve a higher transfer rate. All ATA devices support the slowest mode -- Mode 0. By accessing the information registers (using Mode 0) on an ATA drive, the CPU is able to determine the maximum transfer rate for the device and configure the ATA controller for optimal performance.
Click to expand...

http://en.wikipedia.org/wiki/PIO_Mode
 
Jakal

Jakal

Tech Monkey
Programmed Input / Output. Basically working off of the generic commands through bios. Reduces read and write speed, as you've noticed, tremendously. Ultra Direct Memory Access or UDMA is newer but has been out for many years. UDMA-6 is the fastest at 133mb/s, where as the first mode or UDMA-0 is only 16mb/s. It's older technology being outdated by todays Serial ATA allowing for SATA-II @ 300Gb/s. We'll soon be looking at faster transfer rates of 600gb/s with SATA-III. Sweet!
 
S

spiffyp

Obliviot
To be more specific on why the problem occurs & how to correct it:

After a number of bad reads and/or writes from the specific device in a short time period, WinXP will automatically drop the speed of that device by one step (eg - UDMA2 to UDMA1).
Eventually, this will lead to the drive running in PIO mode & getting horrible throughput.
The normal cause for this (excluding it being a bad drive) is the drive running on the same controller as a low-speed device (eg - DVD-ROM, CD-RW, Zip), bad driver install or bad/wonky BIOS configuration.
To manually set the speed of the drive back to the correct UDMA mode, go to the properties of the IDE controller in question from the Device Manager. There will be a tab there listing all devices connected to the controller & their current speeds. It will also tell you if Windows has reduced the speed & allow you to set the speed to whatever you want.

Hope that clears things up a bit!
 
D

dloneranger

Obliviot
Sorry for the late bump of the post

If those fixes still don't take it out of PIO mode, go to device manager and uninstall the channel that has drive with PIO mode set and reboot (and then because it's windows, reboot again when it rediscovers the new hardware)
That's always fixed it for me - apart from once when I had to uninstall the controller as well
 
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