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axxxxe 05-21-2009 08:24 AM

Ok to copy to smaller destination volume if source volume isn't full?
Is it ok to do "Backup - all files" to a destination volume that's smaller than the source volume if the source volume isn't full? There's no way I'm going to fill the 650G disk on my new iMac anytime soon and I may have access to a cheap 500G external disk...

I do want the destination volume to be bootable.

dnanian 05-21-2009 10:20 AM

Yes, no problem. Make sure the destination is properly partitioned: GUID for an Intel Mac, Apple Partition Map for Power PC.

sjk 05-21-2009 05:41 PM

A couple questions related to SD! backups and partitioning …

If APM is used presumably bootable SD! backups volumes for Intel and PowerPC Macs can co-exist on a single drive? And it would be possible to clone from the Intel backup volume on the APM drive to a bootable volume of a GPT drive on an Intel Mac?

dnanian 05-21-2009 05:51 PM

Well, sort of. Basically, APM works, but under Leopard Intel Macs won't show APM copies as bootable, even though they can be selected with Option+power on.

Copying from APM -> GUID (under Leopard) will work, yes.

sjk 05-21-2009 06:29 PM

Thanks for the helpful, speedy response.

sjk 05-25-2009 03:29 PM


Originally Posted by dnanian (Post 24776)
, but under Leopard Intel Macs won't show APM copies as bootable, even though they can be selected with Option+power on.

Bootable volumes on my APM drive do show up under System Preferences > Startup Disk on my Mac mini 2009 running 10.5.7. Even the Leopard volume installed from my iMac G5 though I didn't try booting from it.


Copying from APM -> GUID (under Leopard) will work, yes.
I haven't need to do that (yet), but the inverse (GPT -> APM) worked fine yesterday

I created a single volume GPT sparse bundle disk image, installed Leopard on it from the mini, cloned the volume to the APM drive using SD!, and successfully booted from it. Using the sparse bundle made this much easier/faster than my original plan of creating a temporary standard volume on a GPT drive to do the Intel-bootable install on and copy that to the APM drive would have been.

In addition to the install-to-sparse-bundle discovery I also was able to non-destructively repartition the APM drive using Disk Utility and create the Intel-bootable volume (after running iDefrag Lite on the original PPC-bootable volume, though it could have been slightly faster restoring the recent backup). I found plenty of outdated info about that around the web before deciding to check it myself (having the backup as a safety net).

I've read that some PPC Macs can boot from volumes on GPT drives but suspected my wife's older eMac wouldn't so there was no compelling reason to convert the external backup boot drive from APM to GPT. Now that hardware/software support for APM has improved for Intel-based Macs it's not clear what advantages, if any, GTP might have that would matter to me.

dnanian 05-25-2009 03:45 PM

That's a change they've made, then - which is curious, because they made the opposite change in one of the other 10.5.x updates.

I don't think any PPC Macs can boot from GPT (although obviously I can't test all of them): I don't think Open Firmware was updated to recognize it...

GPT/GUID's advantage is known to Apple - obviously, they wouldn't be moving to it without reason - but apart from the BootCamp support, I'm not sure what exactly it might be. Perhaps it can support larger volumes... or is more flexible in other ways.

sjk 05-25-2009 04:26 PM

No surprise that Apple giveth and taketh away with apparent haphazardness.

There's a Mac OS X Hints comment claiming booting a Quad G5 from a GPT drive volume.

Ahh, I'd overlooked Boot Camp support being an obvious example of necessitated GPT usage.

I noticed comments about APM vs. GPT volume size limits in Rentzsch's Intel-based Mac Boot Incompatibility article (which may be out-of-date in spots).

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