I burn 2 discs at once all the time using 2 copies of toast.
I'm sure the only speed limit would be your hard drive (transferring data to the burners), not the IDE bus... I'm kind of amazed anyone even mentions it, that's just silly.
I use a RAID-0 for my hard drives and have no problems. I don't know about anybody else though.
I get the feeling sometimes that the hard drive is slowing, but if the burning is all that's going on, it works fine.
Slug, Nobody is saying you CAN'T burn two discs at once, what I am saying and I have found in my own testing is that burning two simultaneous discs or copying a disc on the fly to a blank with two superdrives is OPTIMIZED when using separate buses, or completely removing the drives from the antiquated shared IDE channel.
It's not silly and your comment is ignorant.
I have a RAID 0 Mac Pro 3.0Ghz with 4GB of RAM and with the stock configuration, if I put one DVD in one drive and a blank in the other and tried to copy that DVD (unprotected) it would take FOREVER.
The optical drives DO NOT QUEUE DATA like a hard drive. If you READ on ONE and WRITE on the other, it doesn't happen at the SAME TIME which causes the lag. This is the entire reason why SCSI ruled the roost in high end applications. Where IDE would choke with mutiple requests to read or write data to multiple devices, SCSI could queue the data and have all the devices on one chain read/write simultaneously. IDE (in this incarnation) is not a high end bus and when saturated with multiple commands does not prioritize events.
Now, that all goes out the window when you put the burners on their OWN SEPARATE BUS!! What you fail to realize is that you have two optical drives on ONE IDE bus and simultaneous transfers do not happen with that connection!
You are kidding yourself and the performance of your machine if you don't put each drive on a separate bus!!!
The weakest link in that chain is the IDE bus with TWO BURNERS sharing that bus. IDE can't READ and WRITE to two different devices at the same time, hence all the problems I can demonstrate all day everyday doing what I do with my machine.
LOL
It is what it is and you are not realizing the full potential of two superdrives unless you are just a casual user, which I am not.
So here are the facts:
Two drives on one IDE bus = not the optimal config, impossible to read data or write to/from both devices at the same time.
One Drive on IDE, One drive on SATA = Better, allows simultaneous reads/writes to each optical drive
Both drives on SATA = Best performance