The Old Joel on Software Forum: Part 3 (of 5)

Virtual Macs?

To assist us in QA / configuration testing of our Mac product I'd like to set up a machine that can run multiple versions of OS/X in different "virtual machines" akin to what VMWare does on Intel boxes.

It would be really nice to have an easy way to revert the entire hard drive back to a clean install state with one click, too.

Any suggestions?

Joel Spolsky
Tuesday, January 6, 2004

The only product I know of that does this is MacOnLinux

http://www.maconlinux.org/

But it doesn't look like the website has been updated in a while. And you'd have to run some version of LinuxPPC.

Also it's possible, given an old enough Mac, to install several versions of Mac OS X, given that they each have their own partition. This isn't really as nice as having a vmware like product for Mac OS X.

Of course, neither of these lets you easily roll back changes.

Dylan Adams
Tuesday, January 6, 2004

I don't know of a "virtual mac" solution, but it's very easy to re-image a Mac to a clean configuration, and test with different versions of Mac OS X.

The ASR (Apple Software Restore) software that comes with Mac OS X will take care of the entire process, and it can even be scripted.

The basic process involves setting up OSX on two partitions (or two different physical drives), then creating an image of one while booted off the other. Once you've got the images, you can erase and re-install the OS (and any applications) in a few minutes.

Type "man asr" in a Terminal window for details.

-Mark
(uses ASR to setup build farm macs)

Mark Bessey
Tuesday, January 6, 2004

Now this is the guy who bashed macs for their small market share. Where is your integrity, Joel? :)

Passater
Tuesday, January 6, 2004

I've got to do similar testing. I went over to best buy & bought an 80GB firewire HDD for $99 (post rebate). Partitioned it 8 ways, and then loaded different versions of OS 9 and X on it. Since it's only up to 10.3, there are 4 spare partitions for 'clean' installs.

Then just hold down the 'option' key while the machine's booting to select which partition to boot off of.

Lally Singh
Tuesday, January 6, 2004

Get a Firewire harddrive and partition it for separate versions of OS X.

For easy rolling back to defined states check out CarbonCopy: http://software.bombich.com/ccc.html

For further questions check out DiveIntoOSX: http://diveintoosx.org and many other websites

Johnny
Tuesday, January 6, 2004

Thanks for all the tips!

I never "bashed macs" for low market share. I said that if Macs have, say, 4% market share (I think it's now down to about 2) then it's not economically worth porting if it's going to cost more than about 4% of the cost of your original version.

Because OS/X is basically Unix, when we ported FogBUGZ to Unix we got the Mac version at less than 1% of the cost of the original version, so it was worth it.

Next question: can you boot off a partition on a hard drive connected to an iBook via FireWire?

Joel Spolsky
Tuesday, January 6, 2004

oh never mind I see you just answered that. Cool! Thanks!

Joel Spolsky
Tuesday, January 6, 2004

Thought I saw that Apple went over the 5% mark. At least that was what was announced at MacWorld.

Bill K
Tuesday, January 6, 2004

At the company I am working at we purchased eMacs for testing purposes. They are really low end budget machines so might fit your bill. There's no Virtual VMs so you'll probably want to have at least 2 (for the various major versions of OSX i suppose)?

Li-fan Chen
Tuesday, January 6, 2004

IDC claims 2.3%:

http://news.com.com/2100-1040-1027370.html

Apple is so good at twisting numbers I would never trust anything from them. They have a nifty way of doing things like quoting "retail market share" where they have a higher percentage because, uh, Dell is excluded.

Joel Spolsky
Tuesday, January 6, 2004

Joel, be sure to check out the Lacie D2's for your Mac. I just bought my wife one for Christmas. Very nice.

Mike
Tuesday, January 6, 2004

Welcome to the club, Joel, here's your Kool-Aid. :-)

OS X will boot to external firewire hard drives, including iPods--excuse me, Apple-brand bus-powered external FireWire hard drives. (Gotta get the purchase order past the boss somehow!) And any G4 or newer Mac (or white G3 iBook) can be put into "target disk mode"--power on and when you hear the chime, press and hold 'T' on the keyboard. In a few seconds you'll see a blue & yellow FireWire logo screen. Congradulations, you just turned your $3,000 G5 into a big external FW HD. When done, just hit the power or (if you have one) reset button.

Imagine you have a good mac and a dead one. Put the good one into TDM, connect the two with a 6-6 FW cable, power on the bad one with the option key pressed, and you can boot off the good Mac's HD and fix/check the bad one in any number of ways. Or, put the bad one into TDM and mount it on the good one.

null fame
Tuesday, January 6, 2004

I don't really want to belabor the point of percentages, which Joel would probably agree is a rather boring topic, but IDC also put Apple at about 7% of new laptop sales last quarter they reported. If glancing around my regular haunts accounts for anything, they sure seem to be picking up steam.

But my real reason for posting is to quibble with Joel's point that if platform-X has a 4% share, it's not economically worth porting if it'll cost you more than about 4% of the original version. Those two percentages are rather meaningless to correlate. It's "economically worth porting" under two main conditions: you can earn more from the sales than you will spend to port it and to support those new customers, and you don't have something more lucrative to spend that effort on.

The money you spent developing the original version is water under the bridge, and that amount has no direct economic relevance to your decision to port. At best, you might use it while predicting your future costs, but even that could be shakey, as porting and writing something new are very different activities.

One final point. You should recognize that computer unit market share is just one part of the story, and sometimes not even a very important one. Cray or SGI (or whatever they are called now) might have only a 0.001% share, but if your application is for weather researchers, Cray might be the best platform to target first. I purposely chose a dramatically skewed example, but the concept can hold true in lesser degrees for other products. Sometimes the relevant number is not among the well-known or IDC-measured numbers.

veal
Wednesday, January 7, 2004

I've just noticed something cool you can do with OSX - mount root as a .dmg filesystem image exported via NFS - so you can export the filesystem from any old machine, not just a Mac, as you don't need to worry about dealing with HFS+ weirdness on the server side any more. Plus you can roll back by just replacing the broken dmg file.

See, for example: http://www.bombich.com/mactips/nbas.html

And as for being able to boot from Firewire, that Firewire disk could be another Mac in target mode, or an iPod.

</apple propaganda>

Chris Andrews
Wednesday, January 7, 2004