hard drive: slave vs master

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nosredna - 08 Feb 2006 16:44 GMT

I posted this on comp.sys.mac.system two days ago because there's more
traffic there than here, but no one responded. Maybe someone here can
help?

I have a G4/400 (sawtooth) with a 10gig 5400rpm Apple ATA hard drive
plus a 120gig Maxtor 7200rpm ATA drive that I installed myself last
year. Everything is running okay, but I just read a post on Usenet
(referring to a similar situation with a G4 Yikes) that says, "The
device hooked up as Slave suffers a slight performance decrease,
compared to the Master."

Would changing the Maxtor to master indeed make it a bit faster-booting
and running? If so, I'd like to do it, but I was under the impression
that the master drive needs to be on the end of the ribbon cable.
However, according to this Apple technical document:
http://docs.info.apple.com/article.html?artnum=24342
"It makes no difference which connector on the ATA/IDE cable is used in
a standard ATA/IDE setup because the jumpers control master and slave
status, not the cable. As long as one device is jumpered as master and
the other as slave, any two ATA/IDE or ATAPI devices should work
together on a single channel."

My confusion is caused by my G4 manual which says, "If you are
installing a second ATA drive, configure it as the secondary drive." It
also tells me not to use the "cable select" mode.

Does "secondary" mean "slave?" Does that mean that I can't configure the
Apple-installed drive as a secondary (slave) drive?

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void * clvrmnky() - 08 Feb 2006 17:01 GMT

> I have a G4/400 (sawtooth) with a 10gig 5400rpm Apple ATA hard drive
> plus a 120gig Maxtor 7200rpm ATA drive that I installed myself last
> year. Everything is running okay, but I just read a post on Usenet
> (referring to a similar situation with a G4 Yikes) that says, "The
> device hooked up as Slave suffers a slight performance decrease,
> compared to the Master."

There is a slight benefit to being the master. Depending on what you
are doing with that Maxtor, you probably would not see a difference. It
is more important to make slower media like CD/DVD ROM devices the
master (which explains why Apple put the DVD on the second IDE channel
as a master device. The only thing they advise putting on that channel
as a slave is a zipdrive.)

> Would changing the Maxtor to master indeed make it a bit faster-booting
> and running? If so, I'd like to do it, but I was under the impression
> that the master drive needs to be on the end of the ribbon cable.

This is only true for a setup that uses a special cable with both drives
jumpered to "cable select".

> However, according to this Apple technical document:
> http://docs.info.apple.com/article.html?artnum=24342
[quoted text clipped - 3 lines]
> the other as slave, any two ATA/IDE or ATAPI devices should work
> together on a single channel."

Correct. For standard cables it is the controller on the drive that
decides which device is the master and which is not. The two drives
just have to have the jumpers set correctly.

> My confusion is caused by my G4 manual which says, "If you are
> installing a second ATA drive, configure it as the secondary drive." It
> also tells me not to use the "cable select" mode.

This is still consistent with the previous information. The builtin
drive is set to master, so the easiest thing to do is to add a second as
a drive, and add it to the secondary cable. Apple is giving the easiest
instructions for _adding_ a second drive.

The EIDE standard allows you to also use a "special" cable and let that
decide. In this case both drives are set to "cable select" and the
position of the drives decides which is the master and which is the
slave. Apple wisely decided not to go this route.

> Does "secondary" mean "slave?" Does that mean that I can't configure the
> Apple-installed drive as a secondary (slave) drive?

First question: yes. Second question: no, but it may give you little
advantage to do so.

My advice: Unless you have some specific need to increase throughput to
the Maxtor, just leave everything alone. Unless you are streaming
massive amounts of data to that drive (storing MP3s does not count!) you
will hardly know the difference.

Of course, this assumes that your primary, master, drive is the one you
boot from (i.e., has OS X installed to it). If this is not the case,
you should make sure your OS is on the primary drive.

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nosredna - 08 Feb 2006 17:39 GMT

> > I have a G4/400 (sawtooth) with a 10gig 5400rpm Apple ATA hard drive
> > plus a 120gig Maxtor 7200rpm ATA drive that I installed myself last
[quoted text clipped - 55 lines]
> boot from (i.e., has OS X installed to it). If this is not the case,
> you should make sure your OS is on the primary drive.

Thanks for your very thorough and lucid answers. I'm booting from the
drive with OSX on it, which is the slave, which is the 120gig one that I
installed. It sounds like I should switch them around, which, according
to you, only entails switching the jumpers, not physically switching the
two drives (which I didn't look forward to at all!).

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daystartech - 10 Feb 2006 13:18 GMT

There are two ways to configure the IDE/ATA drives.

The first being as Cable select. Both drives have to be set as cable
select via their jumpers. The last drive on the chain will be
recognized as a master. We service a number of Mac systems each day.
Cable select on the Mac does sometimes have issues when one of the
drives is a Western Digital drive. The "easiest to notice symptom" is a
couple of seconds until the system finds the boot drive on startup.

The second way to configure (my favorite because it limits the
variables), is to configure as Master and Slave. You can have the
drives an ANY order on the chain. The master and slave settings are set
via the jumpers. Note though that some drives have a Master/single
setting. This setting is to be used only if the drive is the only drive
on the chain.

The master drive will show up as device 0. It is usually recommended
that the boot drive be set as the device 0 drive. By default, the Mac
will search and boot to the device 0 drive, unless another drive has
been specified. On older systems using newer drives, setting the device
1 drive as the boot when using OSX can result in the dreaded
Prohibitory sign on bootup (you can work around this by downgrading the
disk drivers to the older OS9 drivers).

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Mac Forum / General / Hardware / February 2006

hard drive: slave vs master