Western Digital and CRC

[SUOrangeman]

Like a few of you, I am anxiously awaiting the arrival of my 120GB bundle of joy from Dell. This is, quite possibly, the best $140 I've spent in a long time. (FYI: I am currently *relying* on 100GB of disk space on IBM 60GXPs. While I haven't had any problems to date with the IBMs, this new drive can't get here fast enough ).

In passing this deal on to colleagues, I received a message about WD's lack of CRC checking in the Linux realm. Of course, no real meat evidence was passed on to me at the time. A quick Google search gave me some hits, which I am still going through. Apparently, according to Linux folks, WD does not do CRC error checking in IDE hardware like everybody else (Maxtor, IBM, Seagate, etc.). And this issue has been around for some time.

So, I ask you ... is/was this a real issue? And, why are the Linux folks the only ones aware of this? Has it been resolved?

In one of the links, there was a reference of WD's response to the matter. WD is claiming that this is a Linux-specific issue, as no one else has piped up on the matter.

Do you have a clue? If so, post any appropriate link!

-SUO

 

[SUOrangeman]

Here's what I have found thus far:

The problem

"Quoting Andre Hedrick, Linux ATA developer:

WDC drives blow off the CRC check of UDMA.........This is BAD and STUPID. Several of the OEM chipset makers have allowed this crap to exist. ATA-2 (style) can not handle ATA-3/4 transfer rates without the CRC checks, you end up continuing the DMA writing regardless if you lost data that would have been saved if the UDMA CRC was intact.

This is a pure hardware issue..."

WD's response

"It's possible but this is nothing we have confirmed. However, keep in mind not all AC22100 model drives are UDMA capable. Only AC22100 drives having a CCC code (located on top of drive on main label) of A8-AG, D5-D7, Bx, or Cx are UDMA capable. It may be the AC22100 drives users have apparently claimed problems with were not UDMA capable drives.

In any case, the UDMA capable AC22100 drives meet all applicable UDMA specifications and are fully UDMA compliant. If there's a problem using these drives in Linux the problem most likely lies with the software driver and not the hard drive itself."

Now, the very next question on WD's Linux FAQ included a link to the Ultra-DMA mini-HOWTO. This mini-HOWTO has a "UDMA Blacklist" that contains nothing but WD drives. However, the blacklist only covers 7 WD models. Given that the mini-HOWTO was updated in December 2001, I want to think that any newer WD drives with the same UDMA "flaw" would have been listed.

-SUO