How to design your IDE setup

Most people don't know about the vagaries of IDE design, so I thought I'd share.

First off, if you only have one or two IDE devices, place them on separate channels. For example, you'd put a hard drive on the primary channel, and a CD-ROM on the secondary.

If you have a CD burner, you want it on the OPPOSITE channel from your regular CD-ROM. This lets you get maximum throughput from one drive to the other, reducing your risk of burning a coaster.

If you have a second hard drive, you probably bought it so you could expand your storage space, so you probably bought a bigger. I recommend putting it on the same channel as your first hard drive, both for reasons of cable length, and to make your installs from CD-ROM go faster.

If you have both an extra hard drive and a CD-burner, you've maxed out your IDE setup. I recommend, at this point, putting your CD-ROM and the larger hard drive on one channel, and your CD burner and the smaller hard drive on the other. This lets you burn CDs from your larger drive and the CD-ROM with the highest degree of confidence.

If you have a Zip drive, it really doesn't make much difference where you put it, as the bus is definitely NOT your bottleneck. The same goes for LS-120 drives, and similar removable devices.

If you've got multiple, different speed controllers, it goes without saying that you need to put the faster drives on the faster controller.

If you're running Windows 95, make sure you enable DMA! The performance difference can be substantial, and it's so quick to do. Just go to Device Manager (either hold the windows key and hit break, or go to start/settings/control panel/system, or right click on my computer and hit properties, or any of a number of other shortcuts). Then double-click on the drive, and hit the little DMA checkbox.

It's important to note, when using IDE, the lowest common denominator rules. Therefore, even though your Hard Drive might be DMA/33, if it is on the same channel as a non-DMA CD-Burner, the hard drive will not be able to use its DMA capabilities. This also goes the same for the various DMA speeds: with a DMA/66 drive on the same channel as a DMA/100, both devices will still run at DMA/66 speeds. You get the picture.

Therefore, if you're really dead set on staying away from SCSI, but still want high performace mass data storage, it's worth your time to either buy a motherboard with more than 2 IDE channels or buy a secondary IDE controller. This is also great when copying large amounts of data from one device to the other: when one device on a channel is being accessed, the other device on the channel will be dormant -- this can cause terrible slowdowns when ripping CDs, and big problems when cutting CDs when the source is on the same channel as the destination device.

My Setup: I've got a DMA/66 Hard drive on my primary Channel and a DMA/33 DVD-ROM and non-DMA 2x CD-Burner on the secondary channel. Normally I would want to put the DVD-ROM on an opposite channel from the burner, but I can't because on the hard drive is DMA/66, and I want the speed. Therefore I'm not using the DMA capabilities of my DVD drive, which is a shame because it adds a lot of CPU overhead and the transfer speed suffers. This isn't a huge problem, however, because I have a fast processor and the CD-Burner is only 2x, so even in non-DMA mode my DVD-ROM drive can still give it enough data per second to avoid a buffer underrun.

Ah, an IDE write-up! I must add my 2 cents! (Yes, I shall proceed to enter 2 pennys into my floppy drive.)

Now then, Superunknown_GP, is correct on all counts, but lucky guys, like myself, have 4, yes count 'em, 4 IDE channels.

Let me show off.

Let me explain.

Some newer motherboards, like my own KT7-RAID, have 4 IDE channels, two of which are ATA/100 or RAID. Nice, huh? Now then, these extra channels should be used exclusively for hard drives. I say this, because no other drives will go that speed.

Remember this: Hard drives always get the fastest channels, but use xunker's lowest common denominator rules. Period.

Now then, my monster
I mean my setup.

Chrono's Setup

I have 2 20Gb ATA/66 hard drives at RAID 0 (Striping) on the 2 ATA/100 channels. I have my DVD-Rom on my ATA/66 Primary channel, and my CD-burner on my ATA/66 secondary channel. See? Maxamum throughput at all times!

If you're using Linux, you will also want to do fun stuff with DMA as well, as enabling this will significantly speed up your hard drive access speeds. However, this being Linux, it's not quite as easy as "tick a box". You need to instead get acquainted with the hdparm command. There's lots of different stuff that you can do with this to improve IDE performance, but for DMA you need to do the following:-

hdparm -d1 <drive name>
e.g. hdparm -d1 /dev/hda
(for obvious reasons you're going to need to be root for this!)

This needs to be done on each bootup, so I'd advise putting it on your /etc/rc.d/rc.local or similar (depending on your particular distribution)