Startup from External Drive and Automatically Unmount Internal Drive

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TaliesinSoft - 30 Dec 2005 20:51 GMT

My SO has a PowerBook G4, a so-called TiBook. Because the internal drive is
insufficient to hold all of her applications and documents and such we
configured it with the intention that it would boot off of an external
Firewire drive that is much larger than the internal drive. The Startup Disk
is set to the external drive. All is working well with two exceptions....

a) Subsequent to a shut down a startup will occur on the internal drive and
not the designated startup drive.

b) An AppleScript initiated upon startup and which has a 60 second delay will
not eject the internal drive, but a subsequent drag and drop on the eject
symbol will.

The ideal situation, that which we would like to have in effect, is that
whenever the PowerBook is started that it always by default starts from the
external drive and that the internal drive is ejected.

Suggestions or solutions will be appreciated.

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James L. Ryan -- TaliesinSoft

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matt neuburg - 30 Dec 2005 22:07 GMT

> My SO has a PowerBook G4, a so-called TiBook. Because the internal drive is
> insufficient to hold all of her applications and documents and such we
[quoted text clipped - 8 lines]
> whenever the PowerBook is started that it always by default starts from the
> external drive

That is indeed the way it is supposed to work. (I have two machines that
work this way.) If you are setting the startup disk properly, I don't
understand why the computer would "forget" the setting. Double-check the
setting in the Startup pref pane.

> and that the internal drive is ejected.

That part makes no sense to me, so I'm ignoring it. Why would you want
to do that? What would it mean, anyway? m.

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matt neuburg, phd = matt@tidbits.com, http://www.tidbits.com/matt/
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AppleScript - http://www.amazon.com/exec/obidos/ASIN/0596005571
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TaliesinSoft - 30 Dec 2005 22:42 GMT

[responding to my stating that subsequent to startup from an external drive I
would like to unmount the internal drive]

> That part makes no sense to me, so I'm ignoring it. Why would you want
> to do that? What would it mean, anyway

This was a precautionary measure. The internal drive on the computer in
question is shortly to be replaced. Given that the complete environment
because of the low capacity of the internal drive is now on an external drive
of sufficient capacity, the unmounting of the internal drive was to prevent
anything being placed on it. This is so that when the new internal is
installed it will be a simple task to clone the curent external to tht
internal. (I hope that all makes sense!)

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James L. Ryan -- TaliesinSoft

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Warren Oates - 31 Dec 2005 13:35 GMT

> This was a precautionary measure. The internal drive on the computer in
> question is shortly to be replaced. Given that the complete environment
[quoted text clipped - 3 lines]
> installed it will be a simple task to clone the curent external to tht
> internal. (I hope that all makes sense!)

I don't know why your external drive won't boot. Are you absolutely sure
that it's bootable? Have you tried holding down the Opt key during
startup to see if it appears on the boot screen?

As for automatically unmounting a drive, I'm not good at shell
scripting, but a simple grep through df would find the /dev entry
associated with its mount point, and then it could be unmounted with
disktool (no man pages anymore, type it at the prompt to get its usage)
or diskutil.

Lord, I hate it when I talk like a geek.

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W. Oates
"I thought I was the last son of Krypton,
but you people keep popping up." -- Clark Kent

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TaliesinSoft - 31 Dec 2005 16:04 GMT

> I don't know why your external drive won't boot. Are you absolutely sure
> that it's bootable? Have you tried holding down the Opt key during startup
> to see if it appears on the boot screen?

The external drive in question, a LaCie 160 GB Firewire, is indeed bootable.
It's just that it won't boot after a shut-down but will boot after a restart.

> As for automatically unmounting a drive, I'm not good at shell scripting,
> but a simple grep through df would find the /dev entry associated with its
> mount point, and then it could be unmounted with disktool (no man pages
> anymore, type it at the prompt to get its usage) or diskutil.

The attempted automated eject of the internal drive is via the following
AppleScript....

tell application "Finder"
    if (exists the disk "Macintosh HD") then
        eject "Macintosh HD"
    end if
end tell

This script works as intended if the target drive is anything but the
internal drive. Interestingly the internal drive can be ejected by dragging
and dropping onto the eject symbol in the dock.

> Lord, I hate it when I talk like a geek.

Many thanks for replying, even if you did sound a bit geekish :-)

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James L. Ryan -- TaliesinSoft

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matt neuburg - 31 Dec 2005 15:31 GMT

> [responding to my stating that subsequent to startup from an external drive I
> would like to unmount the internal drive]
[quoted text clipped - 3 lines]
>
> This was a precautionary measure

But it could be the cause of the problem (i.e. why the computer is
failing to remember correctly that the exrternal drive is the startup
drive). So why complicate the matter? Just do what works.

>the unmounting of the internal drive was to prevent
> anything being placed on it

But nothing will be (unless you do so). m.

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John Johnson - 31 Dec 2005 05:50 GMT

> > My SO has a PowerBook G4, a so-called TiBook. Because the internal drive is
> > insufficient to hold all of her applications and documents and such we
[quoted text clipped - 13 lines]
> understand why the computer would "forget" the setting. Double-check the
> setting in the Startup pref pane.

Could a failing PRAM battery cause this? Should the OP consider
replacing it while the machine is open anyway? The older PowerBooks
seemed to want a new one after 4 years or so, but I don't know how
improved battery technology has affected this, if at all.

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Later,
John

johajohn@indianahoosiers.edu

'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.

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TaliesinSoft - 31 Dec 2005 06:08 GMT

>>> My SO has a PowerBook G4, a so-called TiBook. Because the internal drive is
>>> insufficient to hold all of her applications and documents and such we
[quoted text clipped - 19 lines]
> seemed to want a new one after 4 years or so, but I don't know how
> improved battery technology has affected this, if at all.

I'm hesitant to think thee is a PRAM battery problem given that the PowerBook
was just returned from Apple's repair service where the motherboard was
replaced.

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James L. Ryan -- TaliesinSoft

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John Johnson - 31 Dec 2005 06:19 GMT

> >>> My SO has a PowerBook G4, a so-called TiBook. Because the internal drive
> >>> is
[quoted text clipped - 26 lines]
> was just returned from Apple's repair service where the motherboard was
> replaced.

hmmm. Does Apple replace the PRAM battery with the motherboard? I don't
know about these things. Still, if the PRAM battery were causing this
preference to reset, it should be causing other preferences to reset
(and quite possibly the date/time unless you're using a time server), so
it's fairly easy to check.

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Later,
John

johajohn@indianahoosiers.edu

'indiana' is a 'nolnn' and 'hoosier' is a 'solkk'. Indiana doesn't solkk.

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TaliesinSoft - 31 Dec 2005 06:38 GMT

> hmmm. Does Apple replace the PRAM battery with the motherboard? I don't
> know about these things. Still, if the PRAM battery were causing this
> preference to reset, it should be causing other preferences to reset
> (and quite possibly the date/time unless you're using a time server), so
> it's fairly easy to check.

John,

The time remains correctly set and there doesn't seem to be any problems
other than the inability to boot from the specified drive.

Jim

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James L. Ryan -- TaliesinSoft

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matt neuburg - 31 Dec 2005 15:31 GMT

> > hmmm. Does Apple replace the PRAM battery with the motherboard? I don't
> > know about these things. Still, if the PRAM battery were causing this
[quoted text clipped - 6 lines]
> The time remains correctly set and there doesn't seem to be any problems
> other than the inability to boot from the specified drive.

Still, it couldn't hurt to reset PRAM. Actually what I would do is reset
Open Firmware (this is where the startup disk setting is remembered). m.

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TaliesinSoft - 31 Dec 2005 16:11 GMT

> Still, it couldn't hurt to reset PRAM. Actually what I would do is reset
> Open Firmware (this is where the startup disk setting is remembered). m.

Matt,

I'll give it a try as soon as I can and will report back if that made a
difference.

Many thanks for the suggestion.

Jim

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James L. Ryan -- TaliesinSoft

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Mac Forum / General / Portable Macs / December 2005

Startup from External Drive and Automatically Unmount Internal Drive