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Max · Feb 13, 2009, 02:42 AM

This is an embarrassingly dumb question...

At one time I partitioned an old external drive and created a volume that was a duplicate of one of my original installation disks (“Mac OS X Install Disc 1”). That volume appears (as a bootable disk) in the Finder and sidebar along with my other drives. But (here’s the embarrassingly dumb part), I don’t recall how I did it!

Recently, I got DiskWarrior, and decided to create an image of the DVD. There were several choices: Compressed, Read-Only, Read-Write, and CD/DVD Master. The “primary” default choices seem to be Compressed, followed by Read-Only. The other two (Read-Write, and CD/DVD Master) seem to be third and fourth “secondary” choices. I believe that most image files you get when you download apps and upgrades are “Compressed,” and the “Read-Only” format might be desired if you are creating your own images, and aren’t concerned about saving a few gigs of disk space.

Regardless of what format I might use to create the disk image, it doesn’t appear that the result would be useful as a “volume” that I could boot from (as if I were using the actual DiskWarrior DVD), the same way I can boot from the “Mac OS X Install Disc 1” volume I created .

Could someone clarify all of this for me?

Many thanks.

TETENAL · Feb 13, 2009, 02:56 AM

You can boot from the partition on your hard disk since that is an actual volume.

You can not boot from a disk image since that is not an actual volume. It is an image of a volume. Only when it is mounted there is an actual volume appearing for that disk image. But when your computer is booting there is no operating system there, that could mount a disk image.

Max · Feb 13, 2009, 03:06 AM

Originally Posted by TETENAL

You can boot from the partition on your hard disk since that is an actual volume.

You can not boot from a disk image since that is not an actual volume. It is an image of a volume. Only when it is mounted there is an actual volume appearing for that disk image. But when your computer is booting there is no operating system there, that could mount a disk image.

How do I create a "volume" from a DVD (which obviously would be bootable if the DVD has the OS on it, and non-bootable otherwise)? I did it with my original “Mac OS X Install Disc 1,” but completely forgot how.

Big Mac · Feb 13, 2009, 06:04 AM

By creating a disk image of the disc in question and then burning it to a DVD using Disk Utility or Toast.

Max · Feb 13, 2009, 06:23 AM

Originally Posted by Big Mac

By creating a disk image of the disc in question and then burning it to a DVD using Disk Utility or Toast.

????

I don't want to burn a copy of the DVD, I want to create a "software volume"—a copy of the DVD placed onto a partition on one of my external hard drives, such that the copy looks, feels, and behaves as if it were the physical DVD.

mattyb · Feb 13, 2009, 07:11 AM

Try this.

Simon · Feb 13, 2009, 07:14 AM

/Applications/Utilities/Disk Utility > New > New image from ...

That will save a disk image of your DVD to a file. When you mount that disk image you will get a volume that behaves like the actual DVD.

Max · Feb 13, 2009, 07:52 AM

Originally Posted by mattyb

Try this.

Can you be a bit more specific? Which article/story should I look at on that page?

Max · Feb 13, 2009, 08:03 AM

Originally Posted by Simon

/Applications/Utilities/Disk Utility > New > New image from ...

That will save a disk image of your DVD to a file. When you mount that disk image you will get a volume that behaves like the actual DVD.

I want to create a "virtual hard drive" (for want of a better term), that I can use as if it were a physical medium. That's what I did when I created a "copy" of my “Mac OS X Install Disc 1” on a partition on an old external drive: That partition appears as a stand-alone volume, with all of the properties of the actual “Mac OS X Install Disc 1” DVD—it shows up as a startup drive in the Startup Disk prefs pane that can be selected as my boot drive, the same way I can insert the “Mac OS X Install Disc 1” DVD and select that to boot from at startup.

Spheric Harlot · Feb 13, 2009, 08:20 AM

Originally Posted by Max

Can you be a bit more specific? Which article/story should I look at on that page?

There is only one article on that page, and it is titled "How to clone the Leopard Install DVD to an external FireWire drive"

Pro hint:

Start with the segment just after the introduction and description of why he wrote this article.
It begins:

Originally Posted by TFA

Here's what I did. I have a MacBook. It contains only one system, Leopard. It is booted from the internal drive, running Leopard.

I inserted the commercially available Leopard installer DVD into the MacBook's optical drive...

Simon · Feb 13, 2009, 08:36 AM

Originally Posted by Max

I want to create a "virtual hard drive" (for want of a better term), that I can use as if it were a physical medium. That's what I did when I created a "copy" of my “Mac OS X Install Disc 1” on a partition on an old external drive: That partition appears as a stand-alone volume, with all of the properties of the actual “Mac OS X Install Disc 1” DVD—it shows up as a startup drive in the Startup Disk prefs pane that can be selected as my boot drive, the same way I can insert the “Mac OS X Install Disc 1” DVD and select that to boot from at startup.

You cannot boot from the Leopard image because the image would have to be mounted at boot time. And the boot loader doesn't know how to do that. There's something called netbooting which does something similar, but it involves a dedicated host that serves the boot image.

What you can do however is make a clone (Disk Utility > Restore) of the Leopard install DVD or of a working Leopard installation onto an actual physical drive (USB/FW disk, iPod, flash memory stick, etc.) and boot from that. Hold alt/opt while booting and the boot loader will pop up allowing you to select your clone.

Max · Feb 13, 2009, 08:46 AM

Originally Posted by Spheric Harlot

There is only one article on that page, and it is titled "How to clone the Leopard Install DVD to an external FireWire drive"

Pro hint:

Start with the segment just after the introduction and description of why he wrote this article.
It begins:

Well, for some unknown reason, the link mattyb provided resolved to this: <http://www.macfixit.com/index.php>. Now, however, it resolves to the correct page.

A quick read indicates that what is being described is not (AFAIR) how I did it, though it does have many similarities (which I guess is to be expected). And, IIRC, it wasn't all that complicated to do—it couldn't have been, as I was (and still am) very new to OS X at the time I did it (I'm a recent OS 9 migrator).

But thanks to both of you (mattyb and you) for pointing me to the article.

Art Vandelay · Feb 13, 2009, 10:15 AM

The linked article has an unnecessary step involved. You do not need to make an image of the DVD first. You can simply clone the DVD directly to a partition on a disk using Disk Utility's Restore feature.

Max · Feb 13, 2009, 01:27 PM

Originally Posted by Simon

...
...

What you can do however is make a clone (Disk Utility > Restore) of the Leopard install DVD or of a working Leopard installation onto an actual physical drive (USB/FW disk, iPod, flash memory stick, etc.) and boot from that. Hold alt/opt while booting and the boot loader will pop up allowing you to select your clone.

If I clone the DiskWarrior DVD to a USB drive, will the resulting “volume” be bootable (as if it were the DiskWarrior DVD itself), or will that only work with a FW drive?

Originally Posted by Art Vandelay

The linked article has an unnecessary step involved. You do not need to make an image of the DVD first. You can simply clone the DVD directly to a partition on a disk using Disk Utility's Restore feature.

Can I clone the DiskWarrior DVD to the drive without first creating a separate partition?

Cold Warrior · Feb 13, 2009, 01:38 PM

A USB drive is bootable for Intel Macs. PPC Macs, no. I didn't see whether you told us what sort of Mac you have.

Art Vandelay · Feb 13, 2009, 01:40 PM

Originally Posted by Max

Can I clone the DiskWarrior DVD to the drive without first creating a separate partition?

If the drive is unused or you don't care about any existing data, then yes. If you want to preserve what's there, you should create a new partition.

Max · Feb 13, 2009, 01:48 PM

Originally Posted by Cold Warrior

A USB drive is bootable for Intel Macs. PPC Macs, no. I didn't see whether you told us what sort of Mac you have.

Hmmm...I created a sig with that info, but it's not showing up (I didn't notice an option to turn it "on"):

iMac (24", 2.8 GHz, 2GB RAM, 320 GB HD) • OS X (10.5.4)

But thanks for reminding me re: Intel vs. PPC (I now recall learning about that).

Max · Feb 13, 2009, 01:50 PM

Originally Posted by Art Vandelay

If the drive is unused or you don't care about any existing data, then yes. If you want to preserve what's there, you should create a new partition.

I do have files on the drive. Does that rule out using it without wiping out those files?

Max · Feb 14, 2009, 01:56 AM

OK, I got it together—finally! (Not too surprising, inasmuch as you all told me how to do it!) Once I sat down and started to play with your explanations/instructions, it all came back to me. I still don't recall when/how I originally learned how to do it, but maybe that will come back to me as well.

Thanks to you all for your help—and your patience and understanding.