View Full Version : Master or slave

John H
30-06-2002, 10:52 AM

This may be a really dumb question, but...

In another post, someone was talking about master and slave in relation to drives. In a post some time ago, there was a comment about making a choice when installing a CD Writer whether it is to be a master or slave.

Is someone able to gently explain what this issue is about? Or refer me to a site where I can read about such things?

I have an external USB CD Writer at the moment and I am thinking about upgrading - my choice would be an internal writer. Why would I set it as master or slave in the installation process?

Good grief, this site does encourage you to display your ignorance to the world...


30-06-2002, 11:06 AM
i don't think it really matters. most pc's i set the cdwriter as slave with the cdrom as master. my own pc has both set as master (think about it ;-))

however for some reason i here some cd writers perform better/worse set as slave. i can only put that down to poor cdwriter firmware.

do not (unless its not avoidable) put cdwriter on the same ide channel (cable) as the hardrive.

30-06-2002, 02:17 PM
My understanding is that the CD writer is better off connected to an IDE port that is separate from the data source that is being written to CD (hard disk, CDROM etc).

e.g. if you had the CD writer on the Secondary IDE, ideally you would have a CDROM as a slave on the Primary IDE.

Heather P
30-06-2002, 03:27 PM
Hi John,

I might have got it wrong - in which case someone knowledgeable will no doubt point out my error - but as far as I am aware master and slave came about through lack of resources.

Way back computers had some built in limitations - they had to draw the line somewhere so allowed some leeway and drew the line. Things progressed much faster and futher than was anticipated so duplicates and double ups happened.

Computers generally have 2 IDE ports. This allows you to connect 2 IDE disk drives. Ample.... 10 years ago. Then came the syquest drives, zip drives, extra drives, CD ROM, CD Writers...

So, if you can only connect 2 drives how do you cope? The answer is use one cable to connect 2 drives to 1 IDE port. To prevent conflicts and allow this to work 1 is called the master, the other the slave. There are small switches or jumpers on the disks which you set so the computer knows which is which.

John H
01-07-2002, 08:55 AM
Hi to the three of you who have replied

Thanks very much for the explanation Heather - it makes really good sense, and no-one has contradicted you! I really wanted to know the significance of master/slave, as the use of that language implies some power relationship - ie one rules the other. From your explanation it seems as though that is not correct, so someone has chosen peculiar language to describe what has happened.

And the other two explanations make sense once I think about it - thanks. I generally burn data backups direct from the hard disk to the CD writer, but sometimes write an image of another CD to hard disk first, and then burn the CD from the image. That suggests that the CD should be the slave on the same IDE port as the hard drive, and that the CD writer should be on the other port. In which case it matters not a jot whether it is master or slave, as there is nothing else on that port (I am assuming that is the case)? Have I understood you correctly?

Thanks again


01-07-2002, 12:12 PM
unless you are doing large amounts of cd coping, set it up as follows-

primary ide master: must be harddrive

primary ide slave: free at the moment

secondary ide master: cdrom

secondary ide slave cdwriter

the idea behind this is the high transfer speed from cd to hardrive and from harddrive to cdwriter. only catch is when you want to copy cd's which normally isn't a problem. if for some reason there is a problem then you can do a cd image to hardrive then burn image from harddrive to cdwriter.

01-07-2002, 01:25 PM
I currently have my computer setup as

Primary IDE Master - HDD
Primary IDE Slave - CDROM

Secondary IDE Master - CD Writer
Secondary IDE Slave - None

It depends on what you are trying to achieve with the writer.

If you are going to do a lot of writing, either HDD to CD or CD to CD then the above solution if preferable, becasue then you do not need to worry about creating an image file when doing CD to CD copying.

If however you haqve a newer system with ATA100 support on it, then you would be better of using Tweak solution as this would still enable to HDD to spin at full speed.

01-07-2002, 03:42 PM
>It depends on what you are trying to achieve with the writer.


>Primary IDE Master - HDD
>Primary IDE Slave - CDROM
>Secondary IDE Master - CD Writer
>Secondary IDE Slave - None
>If you are going to do a lot of writing, either HDD to CD or CD to CD then the above solution if preferable

not quite. its preferable ONLY if you are copying cd to cd.

>If however you haqve a newer system with ATA100 support on it, then you would be better of using Tweak solution as this would still enable to HDD to spin at full speed.

ata100 hasn't got anything to do with it. even an ata33 slow old hardrive still goes way faster than any cd.
having a cd slave to a harddrive can but not always cause the performance of the hardrive to slow down.

at the end of the day it all depends on what works best for a given machine and user.

for ultimate burning use a raid/ata card and give each cd/hardrive its own channel. ie no slaves. also with serial drives just starting to appear..........

the trouble with master/slave setups is the cable can support 2 devices but only accesses one at a time(stand to be corrected here). so to copy from master to slave means data needs to be cached in ram, hence the slowdown and where problems arise.

Heather P
01-07-2002, 06:37 PM

I saw your post earlier, didn't have time to reply, and thought tweak'e was an expert and the best person to give the details. I'm sure he's come up with this on the forum in the past. And look what happens - tweak'e pops up with the answers.

In reply to the terms and the power relationship. I believe, but again could be wrong, that when it comes to both disks trying to use the cable at the same time the master will have precedence so will be faster.

Putting any disk at any point on the cables should work. If you need to optimize perfomance (a bit like souping up the Holden V8 - goes but can do better) or if there are problems switch them around as shown.

It would pay to get the manuals out for the disks before doing it. If you're new to switching jumpers you'll need it.

Chris Wilson
01-07-2002, 07:33 PM
I have just put a CD burner in a friends machine this afternoon, there was a recommendation in the box as to where it should be connected, this was of course master on the second IDE channel, preferably by itself. I am assuming that this is because it will be less likely to give errors this way. Because of the length of cables and the space within this machine, i had to ignore that, and set it up thus;
IDE2- master- CDRW
IDE2-slave CDrom
OK, everything worked, BUT when copying an audio CD, it took over 17 minutes to do it. For everything else, which of course involved using only one CD drive at a time, this arrangement worked fine and dandy.

John H
02-07-2002, 01:14 PM
Once again, thank you to all of you for your responses. I now have an idea of what master and slave means, and why those terms came about, and that switching jumpers depends upon the length of your cords...

No seriously, thank you. I know the basic principles, so first try those and if they don't work efficiently, it sounds as though nothing will explode if I then try another way of doing it.

Thanks again.

Heather P
02-07-2002, 08:44 PM
> and that switching jumpers depends upon the length of your cords...

Quite wrong. Jumpers only work if they are knitted in cable stitch.....

John H
03-07-2002, 09:40 AM
Gee thanks Heather (I think). LOL anyway!

Actually after I posted that comment I realised I had said cords instead of cables... One of those situations where you wish you could edit something AFTER you have posted it!