View Full Version : Slave vs Master IDE Drive

Brian Higgins
04-27-2002, 10:24 AM
I have a PTP in which I installed a IDE drive using the VST UltraTek/66 card. I presently use OS9.1 and every thing works just fine. The IDE drive is bootable.
I would now like to add a second IDE drive to my system on which I plan to install Mac OSX and make it bootable. I have upgraded the VST firmware so that the card should work with OSX. (It is not feasible to repartition the orginal IDE and install OSX)

My question: Should I add the new drive as a slave drive to the original IDE drive or simply add it as another master on the second connector. I like the second possibility so that if I decide not to run OSX I can boot back into the original IDE drive without any hassles and not have to worry about changing jumpers. Are there performance issues I should worry about.

Thanks in advance for any suggestions


04-27-2002, 01:27 PM
IDE, a few guidelines.

Each channel on a IDE bus can only have one Master and one Slave installed.

With a 2 Channel (2cables) host cards you can install one master on each cable with no slaves.

Some drives use "Single" instead of master when a slave is not present. Be aware, if you add a slave to that bus you must change the jumpers on the 'Single' drive to Master. (You also can change the old drive to slave and make the new drive Master, doesn't matter)

The connector on the end of the cable should be used as the Master drives location. The middle connector should be the Slave connector.

There is no limitations on the use of either Master or Slave drives. Either can be used for boot drive wih no considerations needed. Performance is absolutely identical between Master and Slave with all other things being equal.

Since IDE doesn't allow concurrent access, having drives of mixed speeds on a IDE bus does not hurt performance, the bus can only access one drive at a time anyway. (one advantage of scsi is concurrent I/O, multiple drives simultaneously, big advantage in performance. Mixing a slower drive on scsi though will slow the bus to the speed of the slowest device, a disadvantage)

Be careful to figure out any partition scheme before you install data on a new drive.

Hope that helps.


04-27-2002, 01:27 PM
If the card provides for two IDE channels, then your idea is a good one...


Brian Higgins
04-27-2002, 02:17 PM
Ricks, doc,
Thanks so much for the great advice. Now let the fun begin....


Brian Higgins
04-28-2002, 09:46 AM
Well OSX 1.1.4 is working on my PowerTowrPro (500MHz G3). I ended up putting the new IDE drive as a slave on the existing IDE channel. No problems; installation with without a hitch. Installing OSX was a little more tricky. First attempt to use my existing Sonnett installer failed. Seems to be a problem having a IDE card in a particular PCI slot. Could never get it to work. Eventually used Ryan Rempels's XPostFacto 2.2b7 and got things to work.

Again thanks for all the help.


Phone Jockey
05-08-2002, 03:44 PM
I have a similar question. I have a Beige G3 Artemis. I've just purchased a Seagate ATA 100 IDE drive and a Ratoc Combo card through your services.

While I've read through the postings, I haven't seen my exact situation dicussed and I'd like to be sure. I appear to have two separate channels: 1) an ATA with two extra female connectors, a CD-ROM already connected; 2) a (according to System Profiler) SCSI bus with the original hard drive connected (unknown until I do further research whether this is set as "single" or "master") with all male connectors.

Can I avoid unnecessary fussing by just connecting the new hard drive (it has male connectors) to the ATA (CD-ROM connected) bus? If so, what's the best setting for the jumpers?

For the RATOC card, I need an extension cable to get power from one of the unused power connectors over to the jack on the board. Would these cables be generic --something that could be picked up anywhere?


05-08-2002, 04:13 PM

Great card, the Ratoc. Yes, a 4 pin molex is a very generic connector and 'y' splitters or extensions are common. I'd probably get the splitter just in case I ever needed another connector and they are usually around 6 inches long.

Your motherboard has both scsi and ATA busus built in. I have heard that folks have had trouble hooking up hard drives to both. I haven't personally witnessed that though.

I would get a 40pin (80wire) ATA66 or better rated IDE cable and install your new drive on the internal IDE connector on the motherbaord. That drive will need to be configured as Master, or in some cases as 'Single" depending on how the drive manufacturer built the drive. (if there's a single jumper setting that's the one to use when it's the only drive on the cable)

You may have a 40 pin cable already tucked into your computer and plugged into the IDE bus, look and see.

You could install the hard drive on the CD-Rom bus but you will get about half the performance from that slower bus than you would from the IDE hard drive bus.

SCSI buses are NOT ATA buses. They take a different kind of drive, cables and settings. If you purchased an ATA drive and your sure your old drive is scsi they will not combine on the same cable. SCSI has 50 pins internally and 25 pins externally on your machine.

Run Apple System Profiler if you are in doubt as to which drive you have. The devices page will tell you.


[This message has been edited by ricks (edited 08 May 2002).]

05-08-2002, 04:15 PM
Phone Jockey

Sometimes the drive itself has a diagram on it - showing how to set it to a "master" or "slave" - or find the make and model number and go to the website and look it up there. If you have trouble post the make and model. Some of those sites are a pain.

Good luck

Phone Jockey
05-08-2002, 05:25 PM
Thank you ricks and rwm2.

If I understand you correctly, Ricks, I am purchasing an additional IDE cable (as per specs, thanks), connecting one end to the IDE connector on the motherboard, and the other end to the new Seagate Barracuda ATA 100 IDE drive that I've just installed in the bay.

Thanks for the jumper instruction support, rwm2. As it appears that I won't be doing a master/slave hook-up, I may do the online research anyway. It may come in handy in the future.

Thanks also for the details on powering the combo card.
I'm very impressed with the both the generosity and speed of replies.