So, does W2k support UDMA/100?

  • Thread starter Thread starter Dave
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Dave

The knowledge base has numerous articles about this, though I can't discern
a definitive answer. One article says that ATA-100 devices will revert to
ATA-66 w/out the appropriate fix, which seems to be in SP2. I'm using SP4,
yet I can't find the reg entry enabling the higher speed. (I found an
article on the web w/Win2k tips. One of them is to add the reg key "DWORD
value called EnableUDMA66". I looked for this value and it appears not to
be there.)

There's also mention of UDMA/100 drives being erroneously listed as running
in PIO mode, after a fix has been employed. Well, I can tell that when my
Primary Slave is listed as PIO, it's PIO, because it's very slow.

I may have 2 problems. The first is that (I think) my drives are not being
accessed in UDMA/100. The second thing is, Wndows will switch my slave into
PIO if I use power management on the HDDs. Evidently, the time it takes the
drive to spin up to speed is longer than the 4 sec timeout in W2k, before it
reports an error. The shorter I make the time before Windows shuts down the
HDDs the sooner it gets switched in PIO mode (though only the slave).

What's the deal? Is there a fix? Any help will be much appreciated,
because the info I've found is confusing.
 
Dave said:
The knowledge base has numerous articles about this, though I can't discern
a definitive answer. One article says that ATA-100 devices will revert to
ATA-66 w/out the appropriate fix, which seems to be in SP2. I'm using SP4,
yet I can't find the reg entry enabling the higher speed. (I found an
article on the web w/Win2k tips. One of them is to add the reg key "DWORD
value called EnableUDMA66". I looked for this value and it appears not to
be there.)
Click to expand...

So add it. That's what the directions are telling you to do.
 
So add it. That's what the directions are telling you to do.

Fine. But, that's for ATA-66. What about ATA-100? And how do I increase
the ATA driver timeout?
 
Dave said:
Fine. But, that's for ATA-66. What about ATA-100? And how do I increase
the ATA driver timeout?
Click to expand...

SP2 or later will add ATA100 support. Windows might display
an incorrect "PIO" transfer mode after it's applied, see the "More
Information" section here:
http://support.microsoft.com/support/kb/articles/Q260/2/33.ASP

Also note, unless you're running more than two drives you won't
see much (or any) improvement from ATA66 to ATA100. That's
because no single IDE drive (or in many cases, two IDE drives)
can push more than 66MB/sec across the bus.

Rick
 
SP2 or later will add ATA100 support.

That's what I thought the article said, but if I'm supposed to see the
"EnableUDMA66" value in the reg (as the article I cited mentions), it's not
there.

And, the other thing I'm trying to remedy is this:


SYMPTOMS
After you suspending and resume your computer several times, hard disk
performance may be reduced. If you use Device Manager to view the properties
of the IDE channel to which the drive is connected, the Advanced Settings
tab may show that the current transfer mode for the drive is "PIO Mode."
CAUSE
After the Windows IDE/ATAPI Port driver (Atapi.sys) receives a cumulative
total of six time-out or cyclical redundancy check (CRC) errors, the driver
reduces the communications speed (the transfer mode) from the highest Direct
Memory Access (DMA) mode to lower DMA modes in steps. If the driver
continues to receive time-out or CRC errors, the driver eventually reduces
the transfer mode to the slowest mode (PIO mode).
RESOLUTION
Windows 2000
A supported feature that modifies the product's default behavior is now
available from Microsoft, but it is only intended to modify the behavior
that is described in this article. Apply it only to systems that
specifically need it. This feature may receive additional testing.
Therefore, if your system is not severely affected by the lack of this
feature, Microsoft recommends that you wait for the next Windows 2000
service pack that contains this feature.

To obtain this feature immediately, contact Microsoft Product Support
Services. For a complete list of Microsoft Product Support Services phone
numbers and information on support costs, visit the following Microsoft Web
site:




I know that the drive is really in PIO mode because performance is terrible.
I'm asking whether anyone knows what this fix is. I read that the driver
timeout in W2k is 4 sec, which is not enough time for the drive to spin up
(at least not the 7200 RPM drive), so in XP the timeout was increased to 10
sec. How do I increase the timeout value in W2k?

because no single IDE drive (or in many cases, two IDE drives)
can push more than 66MB/sec across the bus.
Click to expand...

Good to know. Thanks.
 
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