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Curious SATA behaviour


Inki

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Out of pure curiosity, I wonder if any of the experts on this forum might be able to shed some light on what could be going on in the following situation. Still, this is not an issue worth making a big a big fuss about, and I am sure that there are better ways of spending time than digging into it if there is no immediately obvious explanation. Anyway, here goes:

The Gigabyte GA-7VT880-L (VIA KT880/VT8237) mainboard allows its SATA ports to be set either into IDE mode or RAID mode through the BIOS.

If the system is used in DOS, everything appears to work fine with both PATA and SATA disks irrespective of which mode SATA is set in – no issue here.

If SATA is in RAID mode and 98SE is installed (on one of two installed PATA disk with an additional SATA disk installed) everything appears to work fine as one might expect – no issue here either.

However, if SATA is in IDE mode and 98SE is installed in the same disk configuration as above, then any access to the SATA disk takes up to five minutes or more to complete (but is eventually completed). Installing 98SE, for example, proceeds quite normally (including the initial disk checks) until 98SE is activated and begins to do the disk accesses, at which point the waiting game begins.

This behaviour does not appear to depend at all on whether VIA drivers are installed or not, what version they are, or whether their SATA/RAID-component is installed or not. It does not seem to depend on the BIOS version either, and I remember having previously observed something like it also on a VIA KT600/VT8237-based mainboard. The behaviour, however, does not occur with Windows 2000 on the same platform, and I assume that it is linked to 98SE or its disk drivers and possibly some incompatibility with VT8237 hardware in this particular mode.

My best guess is that somehow 98SE gets confused by the large number of available IDE ports (I have not yet tested the configuration where I would disable all PATA ports and only have SATA in IDE mode, nor will I shortly due to having other things to do). Still, no confusion is apparent under DOS, and 98SE appears to run, although with the ridiculously long disk access delays it is difficult to be certain of this. Nor have I (yet) observed any indication of disk corruption.

This is not really a problem, because one can always just have the SATA ports set to RAID mode without actually setting up a RAID array, and everything is fine. However, I am just simply amazed by how much resultless activity the system seems to be capable of generating for several minutes over nothing but the simplest SATA disk access in IDE mode.

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Are you using 32-bit disk access or has Windows reverted to realmode (DOS 16-bit)disk access? Check this in the System Properties -> Performance page. If it lists any drives as "MS-DOS compatibility mode", that means it's using realmode BIOS for disk access which slows down significantly.

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Thank you for your suggestion, LLXX. In fact, the SATA drive is accessed through DOS-compatibility mode when set to IDE mode.

However, I suspect that something else is also going on. As an example of what kind of delays are involved: after right-clicking on "My Computer", it takes a full nine and a half minutes for the dialogue box to appear where one can then select "Properties".

Furthermore, when SATA IDE-mode is activated, the Device Manager displays all of the following Hard Disk Controllers:

- Primary IDE Controller (dual fifo)

- Primary IDE Controller (single fifo)

- Secondary IDE Controller (dual fifo)

- Secondary IDE Controller (single fifo)

- Standard Dual PCI IDE Controller

- VIA Bus Master PCI IDE Controller

When one then includes the actual SATA disk, the behaviour with long delays results. All the Disk Controllers and Disks are reported to be "working properly".

I am guessing wildly here, but perhaps with that whole bunch of disk controllers present 98SE might be attempting to simultaneously perform incompatible actions but somehow manages not to crash, and perhaps the hardware RAID management layer is required for 98SE to make sense of the situation.

Maybe it is just not meant to be that this system would work with 98SE if SATA is set to IDE mode. I really have no idea. This is something that I have been wondering about for at least a year or so, and I have usually tested some aspect of it each time that I have re-installed 98SE. Currently I am resigned to thinking that this is a feature and that the reasonable thing to do is just to be happy and stick with the RAID mode.

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However, I suspect that something else is also going on. As an example of what kind of delays are involved: after right-clicking on "My Computer", it takes a full nine and a half minutes for the dialogue box to appear where one can then select "Properties".
I don't think right-clicking on My Computer should produce any disk activity at all. What CPU are you using? My suspicion is that it's an AMD, and there have been reports both this site and other sites that improperly installed CPU will cause major slowdowns.
Furthermore, when SATA IDE-mode is activated, the Device Manager displays all of the following Hard Disk Controllers:

- Primary IDE Controller (dual fifo)

- Primary IDE Controller (single fifo)

- Secondary IDE Controller (dual fifo)

- Secondary IDE Controller (single fifo)

- Standard Dual PCI IDE Controller

- VIA Bus Master PCI IDE Controller

When one then includes the actual SATA disk, the behaviour with long delays results. All the Disk Controllers and Disks are reported to be "working properly".

I am guessing wildly here, but perhaps with that whole bunch of disk controllers present 98SE might be attempting to simultaneously perform incompatible actions but somehow manages not to crash, and perhaps the hardware RAID management layer is required for 98SE to make sense of the situation.

Maybe it is just not meant to be that this system would work with 98SE if SATA is set to IDE mode. I really have no idea. This is something that I have been wondering about for at least a year or so, and I have usually tested some aspect of it each time that I have re-installed 98SE. Currently I am resigned to thinking that this is a feature and that the reasonable thing to do is just to be happy and stick with the RAID mode.

How many HDCs does it show for all the different modes of the SATA controller? For the list you have above, try disabling the (single fifo) IDE controllers so that only the (dual fifo) and the VIA Bus Master PCI IDE Controller are enabled. It seems that the Standard Dual PCI IDE Controller is the root of all the (single fifo) entries.

Also, try booting into Safe Mode, removing ALL of the entries under hard disk controller, and rebooting. Sometimes hidden devices might be conflicting, and they can only be seen in the safemode.

Edited by LLXX
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Are you using 32-bit disk access or has Windows reverted to realmode (DOS 16-bit)disk access? Check this in the System Properties -> Performance page. If it lists any drives as "MS-DOS compatibility mode", that means it's using realmode BIOS for disk access which slows down significantly.

That's because DMA isn't supported in DOS-compatibility mode. That means there will be high processor usage for every HDD access and thus most users won't see more than 4 MB/s!

If HDD benchmark results are fine, you don't have to worry about this problem.

If DMA gets disabled, you would notice right away, because Windows will be slow for even small tasks or when burning a CD, the recording buffer percentage keeps dropping to a real low value.

Edited by RJARRRPCGP
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Thank you for your replies.

First of all, let me emphasize that the disk access delays that I am referring to are of a totally different magnitude than the mere slowing down due to DOS compatibility mode. Think in terms of having to wait ten minutes on an XP3200+ system before you can see the listing of your disk volumes after having double-clicked on "My Computer". These huge delays do not occur whenever the system is in safe mode and all drives are in DOS compatibility mode.

Then let me describe a few cases:

Case 1. If one does a clean install with SATA in IDE mode, or if one does a clean install with SATA disabled and then reboots with SATA in IDE mode, the situation becomes as is described in my previous posting:

- The normal triplet of Hard Disk Controllers is present:

-- Primary IDE Controller (dual fifo)

-- Secondary IDE Controller (dual fifo)

-- VIA Bus Master PCI IDE Controller

- Three additional Hard Disk Controllers appear (the third one is the root for the other two):

-- Primary IDE Controller (single fifo)

-- Secondary IDE Controller (single fifo)

-- Standard Dual PCI IDE Controller

- Ludicrously large SATA access delays occur when the SATA disk is connected.

- The SATA disk, when connected, is accessed in DOS compatibility mode.

- The VIA SATA RAID Controller driver can not be installed.

I have not done a systematic analysis of further options based on this case. However, the mere manual removal the Standard Dual PCI IDE Controller, for example, is not a solution. If that is done, then:

- The SATA disk is accessed in DOS Compatibility mode

- At each reboot the system asks for the driver to be reinstalled.

- If it is reinstalled while the SATA disk is connected there is a risk of the same kind of halt on

error that is described under Case 2.

Case 2. If following Case 1 one reboots with SATA in RAID mode, the situation changes as follows:

- The Primary IDE Controller (dual fifo) shows an error in normal mode.

- If the SATA disk is connected at this point, then the systems halts at a big blue error screen:

-- The Standard Dual PCI IDE Controller does not support a mixed 16-bit and 32-bit access configuration.

-- After restarting, all disks are accessed in DOS compatibility mode and all four Primary and

Secondary IDE controllers show an error in Device Manager in normal mode.

With no SATA disk connected it is possible to proceed by installing the VIA SATA RAID Controller even though the related PCI IDE Controller device is not visible in Device Manager. The situation then becomes the following:

- The normal triplet of Hard Disk Controllers works properly.

- The three additional Hard Disk Controllers no longer appear in normal mode:

-- The two (single fifo) -controllers are visible only in safe mode.

-- The Standard Dual PCI IDE Controller has disappeared.

- The PCI RAID Controller device is now listed under SCSI Drivers as VIA SATA RAID Controller.

- The system functions normally.

Case 3. If one does a clean install with SATA in RAID mode, then:

- The normal triplet of Hard Disk Controllers is present.

- The additional Hard Disk Controllers never appear.

- The PCI RAID Controller device appears, and after installing its driver it is listed under SCSI Drivers

as VIA SATA RAID Controller.

- The system functions normally.

Case 4/Case 5. If following Case 2/Case 3 one reboots with SATA in IDE mode, then:

- No change is apparent among the devices listed in Device Manager either in normal mode or safe mode.

- Ludicrously large SATA access delays occur when the SATA disk is connected.

- The SATA disk, when connected, is accessed in DOS compatibility mode.

Mysterious, is it not?

Edited by Inki
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Your mobo has both IDE and SATA controllers right?

If you're not using the IDE controllers, you should disable them in BIOS.

Sounds about right. My mainboard (EPoX 9NDA3J) would instead end up with driver conflicts amongst the HD controllers if I enabled both SATA and IDE at the same time. Disabling SATA due to not having any solved the problem. I'm sure it would be the same case had it been SATA enabled and IDE disabled.

Oddly, though, my IDE controllers come up single fifo rather than dual fifo.

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