# Performance of IDE master/slave, etc?

## n0n

Hey, I've been messing around with my box lately, and I've had a recurring question of mine pop back into my head, which I've never been able to find a definitive answer to.  Basically, what's the most efficient way to put drives on IDE controllers so that you get the max throughput?  I'm assuming that drives in the "slave" position are probably less efficient than those in the "master," or is that wrong?  If I have to regularly copy data from one hard drive to another, does it make more sense to have them be master/slave, or is it better to have them both be masters on different IDE busses?  I've got a PCI card which gives me two more IDE busses, is that going to be faster or slower than the two that are on my mainboard?

You could probably come up with some more questions yourself, but basically that's what I've been wondering for some time.  I know that I could just buckle down and benchmark some of this stuff myself, but I'm sure that it's been done before.  Google's been somewhat unhelpful because the search terms are generally so widespread.  Anyone have a link or two?  Thanks!

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## BonezTheGoon

Copying data (large amounts) will be better across channels instead of in one channel.  The reason being that the Master drive controls the channel and directs the traffic for both the drives when they are on the same channel.  If you have two hard drives, each a master on their own channel, they can control themselves and therefore work better.  At one point I had my CD-RW as Master and my DVD as slave (same channel) and Nero [yes yes this was back when I used M$ Win2k] reported that it could not copy data straight from the DVD-ROM to the CD-RW given they were on the same channel, copying the data first to the hard disk on the other channel was necessary.  Having an external controller that allows all your devices to be Master is a nice feature.  A slave device does not always have poor performance though, if your master device is otherwise idle your slave device feels no performance hit (in my experience.)  So it greatly depends on what hardware you have where and how you are using it!  If you have two hard disks and one CD-RW I would suggest you have your hard disks both be masters and then have your CD-RW as slave on the second channel.  Then I would generally try to always burn data from the other channel, ie /dev/hda.  

Most of what I said though should probably be considered opinion given there are surely other considerations in different settings that give varied results.  I think that this pretty much sums it up for the majority of the time though.

Regards,

BonezTheGoon

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## broody

Your best bet is to go over the FAQ, specificly this section.

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## n0n

BonezTheGoon: Thanks for the input!

broody: That link is fantastic, thanks!

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