IDE Behavior: Old Wives' Tale or Not

[ArtShapiro]

Does anyone really, truly know whether the conventional wisdom about mixing different "modes" on a single IDE channel is actually true?

That widely held belief maintains that if one has, say, a mode 4 modern drive and an older mode 2 drive (or a CD rom) unit on the same IDE channel, then the channel will operate at the slower device's speed, thus causing a deterioration of performance.

I suspect there are three possible answers:

a). yep
b). nope, the channel will drive each device at its appropriate capability
c). only if they're both requesting I/O at the same time will the drive revert to the speed of the slower device.

Anyone versed in this area?

Art
:confused:

[jokostel]

id shoot for c myself.

[Fingers]

Modern motherboards/IDE controllers can switch modes on the fly, older ones apparently could not.

My links on this topic are about a year old, but here's the most relevant one that comes to mind;

Can I mix Ultra ATA/33 and Ultra ATA/66 drives on the same cable? (http://www.seagate.com/support/kb/disc/ultra_ata_66.html#8) - Seagate FAQ

b is the most correct answer assuming the mobo is at least ATA-66 capable. The slow-down experienced during simultanious drive access is not because the channel reverts to the slower standard for both drives, it is because only one drive may transfer data to/from the controller at a time regardess of what mode the drive(s) are operating in.

[ArtShapiro]

Thanks to Fingers ... that certainly looks authoritative in my book.

This will simplify my life a little - I suspect my situation might be odd enough to relate to everyone without being boring.

My current Soyo K7VTA MB has an interesting bug in that a hard drive on the secondary IDE port, either master or slave, won't be recognized on a soft boot. Really a strange little problem, but reproduced on the three K7VTA's I've owned. One has to do a hard powerdown/powerup to recognize the drive - a real nuisance when installing software and one or more reboots are requested or caused automatically. Because I didn't want to slow down the main hard drive, which is of a faster mode than the drive I usually put in as the second drive, I was forced to purchase and use an aftermarket IDE controller, filling my last PCI slot and causing yet another cable to be snaking around the inside of the machine.

So it sounds like I can move the second hard drive to the primary IDE channel's slave connection without killing the throughput capacity of the primary drive, keep the CD on the secondary master , and remove the aftermarket controller.

Just bought a CD RW unit (Liteon 16x10x40x). Any reason it can't go on the secondary port as slave with the existing CD guy? (Or do I want to stick it on the aftermarket controller?!)

Art

[Fingers]

I wouldn't have any reservations about moving the 2nd HDD to the primary slave position.

The new configuration you suggested should be just fine.

Primary Master - HDD #1
Primary Slave - HDD #2
Secondary Master - CD-Rom or CD-R(W)
Secondary Slave - CD-R(W) or CD-Rom

Save the PCI controller card for a system that needs a 5th IDE device.


I'm moving this over to the Data Storage forum. :)