HD PIO mode vs UDMA

[Homerboy]

C:\ is a IDE Ultra ATA/100 40GB 7200rpm MDT (Magnetic Data Technology) MD400EB-00CPF0
D:\ is a IDE Ultra ATA/66 34.2GB 7200rpm Deskstar 34GXP IBM DPTA-373420

Motherboard support ATA/100 Ultra DMA Mode 5 max.

When C:\ was single drive, by itself on primary ide master, it worked fine.
The drive operated reasonable fast and was listed in device manager as running in ultra dma mode.
BIOS listed it as being ATA/100, dma mode 4.

When I added D:\ on the primary ide channel as slave C:\ started acting up.
C:\ Drive now runs noticeably slower.
C:\ drive is now listed in device manager as running in PIO mode only.
D:\ drive is listed in device manager as running in Ultra DMA mode.

Cable replaced with brand new unit.
Jumpers on drives are correct, I triple checked.
IDE cable placement is correct.

 

[LTC8K6]

When XP detects errors on an IDE device, it progressively slows down that device until no more errors are detected. This could be what happened. To reset this, delete the offending IDE controller, primary or secondary, and let windows redetect it. You may be able to get away with just deleting and redetecting the device.

 

[Homerboy]

Thanks its a Win2k machine though... will give it a try regardless.

 

[BlackMamba]

Have you tried putting one drive on the second chain and seeing if C:\ is still PIO? It would still be better to have one HDD per chain (I'm guessing one would share a chain with an optical drive) for disk to disk copies.

 

[VirtualLarry]

Originally posted by: Homerboy
C:\ is a IDE Ultra ATA/100 40GB 7200rpm MDT (Magnetic Data Technology) MD400EB-00CPF0

That's kind of interesting, I've never heard of that brand before. Judging by the format of the model-number string, I would say that it is a clone/OEM varient of a WD IDE HD.

Btw, LTC8K6 is on the money, about why the HD is slowing down.

As for the problem, it could be either caused by the fact that the two HDs don't really work well together on the same cable, or that the first HD actually has bad sectors or something, but that problem was only noticed after installing the second HD. Btw, did you change the jumpers properly when adding the second HD? WD (or in this case, I assume, their 'evil clone brand') HDs have seperate jumper settings for a Single drive on the channel, vs. Master. (Wait, you said you triple-checked the jumpers, so it's probably not that.)

Try downloading WD's DataLifeguard diagnostics disk, "DLGDIAG.EXE", and try running it on your first HD. If it works (it might not, what with the change in brand/model-name string), then it should be able to tell you if the drive has bad sectors or not.