[linux] Problem with big big hard drive

Ryan Phillips bitman at u.washington.edu
Mon May 26 12:42:06 PDT 2003

I'd just like to iron out a bit of the hard drive terminology used here.
UDMA is not all that new, it was introduced as part of the ATA/ATAPI-4
standard in 1998 to replace regular DMA, which nobody had really used
since its creation in 1996. Since it ran at an astounding 33Mhz (twice
what DMA or PIO modes could pull), the marketing term Ultra ATA/33 was
coined for such drives. What is probably newer than your motherboard is
the 133Mhz speed which was introduced some time after 2000.

EIDE is a term that means many different things at once, and so really
it means nothing at all. Western Digital coined it in 1994 and redefined
it repeatedly to include whatever new technology they had to offer. Even
UDMA was globbed into the term eventually.

The term IDE is even more generic yet, refering to any of the various
ATA standards, with the notable exception of the new Serial ATA interface.

My source for all this information is the Hard Drive Reference Guide.
Hard drives have a fascinating history, so take a look:


More about UDMA:

More about EIDE:

Huge list of hard disk size barriers as old as the 528MB limit:

Dan Sanderson wrote:

> I recently got a brand new Maxtor 7200 RPM 200GB hard drive (Maxtor

> 6Y200PO). This is the Maxtor Ultra Series 8MB cache, Ultra ATA/133. My

> BIOS detects it fine as the secondary slave, and Linux assigns it

> /dev/hdd as appropriate. But any attempt to fdisk /dev/hdd results in

> "Unable to open /dev/hdd," and /var/log/messages to log "hdd: driver not

> present." I'm using kernel 2.4.18-bf2.4 (Debian 3.0). Does anyone have

> any ideas on what "driver not present" means in this context? Anyone

> know what I might be missing?


> The drive came with an Ultra ATA/133 PCI card, which I haven't tried yet

> and originally assumed was optional. This has given me the impression

> that UDMA is rather new, at least relative to my motherboard (please

> correct me if I'm wrong). So I'm learning about Ultra DMA a little

> after the fact. The Linux UDMA Mini-Howto ([1]) says UDMA should be

> backwards compatible with EIDE (without the UDMA bus speed), and I

> shouldn't have to do anything special to get it to work. I don't know

> much about my motherboard except that it's at least a few years old and

> reports itself as "Via Apollo Pro PCISet" on start-up (which I assume

> close to this: http://www.via.com.tw/en/apollo/PRO.jsp). The mini-howto

> mentions a possibly old problem with "TX Pro and other 'Pro' boards,"

> but I don't know enough to know if that applies here, and by now I'm

> probably way off track.

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