IDE question 1

[DannyBoy01]

Hey peeps...

Probably a silly question, but not my area. Anyway, I was spak with someone with who said there are certain whys you can hook up IDE cables on a stand alone machine to improve preformance.

Something, about if you piggy back a CD-Rom and Hard drive of one cable you can lose 20% preformance. If anyone can fill me in that would be great!!!

Thanks,

D-Boy

 

[bcastner]

The whole notion of IDE is that you have a Master controller for the channel, and possibly a slave.

The ideal would be to place your hard disk drive on one channel as Master; your optical devices on the second IDE channel as a Master.

Combining a hard disk (very fast) with an optical device such as a CD ROM (comparatively slow) on the smae IDE buss and channel is not a good idea. Not only does this create competition for buss access doing any CD-to-Disk transfer, it often forces the OS to choose the most common demonitor for the buss speed to devices -- the slowest device always wins.

If you can, place the hard disk on IDE 0 as Master, the optical drive on IDE 1 as master, and do not mix them on the same daisy chain or IDE channel.

 

[micker377]

It is possible that an optical drive (slow CD drive), can slow down a fast (IDE hard drive) drive. It is best to put hard drives on one IDE cable, and other drives on another. A good speed up is to set the hard drives to "DMA" on.

 

[DannyBoy01]

Thanks for your prompt and informative reply.

If you have any links were I can read up on this that would be great. Otherwise thanks again.

 

[micker377]

Read up on which? The IDE cable info, or the " settings?DMA

 

[micker377]

Been watching Yoda too much! That should be "DMA" settings!

 

[DannyBoy01]

DMA Settings I would like info on, yes....

 

[micker377]

Go to Device Manager > IDE Controllers > Primary IDE Channel > Properties > Advanced > Check the DMA box (Win 98) or DMA if available (Win XP). You may get an error "This may cause damage...". Ignore it if the computer is less than 5 years old. Hit OK and reboot. What this does is take the hard drive info from the harddrive directly to the memory (DMA = Direct Memory Access), as opposed to from harddrive to CPU to memory.

 

[cdogg]

The age of your system makes a difference.

It is NOT true that the IDE bus runs at the speed of the slowest device, UNLESS
- your system was built sometime before 1998
[tab]OR
- you have a device that uses PIO Mode

Back then, IDT (Independent Device Timing) wasn't around. IDT is what allows you to mix UDMA modes on the same IDE channel. For example, you could have an ATA/33 (CD-ROM) and an ATA/100 (hard drive) device running at their own speeds on the same channel.

PIO Mode has to use the CPU to access main memory, unlike DMA (Direct Memory Access). If a PIO Mode and ATA device share the same channel, both will run in the slower mode. Most early CD-ROMs only ran in PIO Mode, which is why you hear so many people telling you not to do it. Not many old school techies realize that most CD/DVD-ROM devices today use UDMA mode 2 (ATA/33) with IDT.

Read my last post in this thread for links:
thread751-437954


Next point...
It IS true, however, that transfers between devices on the same channel would be much slower than if they were on different channels. That goes for hard drives, optical devices, and a mix of the two regardless of what UDMA mode they're running at.

Therefore, the best configuration to have depends on your situation. Some peeps like to do a lot of CD-to-CD copying. In such a case, it would make more sense to have the CD-ROM share the Primary IDE with the hard drive, and place the CD Burner on the secondary by itself.


With SATA and PCI IDE controller cards, all this is in the past...


~cdogg
[tab]"All paid jobs absorb and degrade the mind";
[tab][tab]- Aristotle
[tab][navy]For general rules and guidelines to get better answers, click here:[/navy] faq219-2884

 

[teknikal]

I agree. XP has the advanced settings tab in Device Manager that shows you which mode each device on an IDE channel is running at. I've seen cases where two different modes are used at the same time.

tek