Clone Snow Leopard from Leopard?
 

Dave (anyone)

Not my problem; trying to help a friend. While running under Leopard, is it advisable/possible to clone a second volume, a Snow Leopard boot volume, to a third volume, say a blank external? I think the answer is no, but am I correct? (Assuming one was running SD 2.6.1, not an earlier version.) TIA

Good question.

Without searching for Dave's earlier posts about this (yet), my vague understanding is that you always want to copy Snow Leopard volumes with SD! running on SL.

But what defines a "Snow Leopard volume" is still a bit unclear; does it mean any volume that SL has touched even if it's non-bootable? For example, if you've made changes on a volume of an external drive while running SL can that drive/volume still be used and copied with SD! on Leopard? Hard to imagine being limited to using drives/volumes under different OS X releases even if they shouldn't be copied while running an earlier one.

Instead of just answering here maybe Dave could write up a brief, easily referenced FAQ post on this topic for the sake of anyone seeking accurate information about it.

In general, it's unwise to copy a volume created by a "later" version of the OS with a "former" version.

What about copying a volume that's used by a "later" OS version that might (but not necessarily) have also been created on it?

Actually, I'm not entirely sure what you meant by "created" in your reply.

I have an external drive containing three volumes, all created under Leopard. Two are small bootable volumes, one each for PPC and Intel systems. The other is used for Time Machine backups, used only on my single Intel system. After upgrading the Intel system to SL I'd also like to upgrade the Intel-bootable volume on the external drive and use the TM volume under SL. The PPC-bootable volume (with 10.5.8) will remain relatively static, maybe doing an occasional Apple security update while booted from it. All three volumes mount when the drive is attached to any system and I manually unmount those not being used.

Post-upgrade, presumably it'll be best never to copy the two SL volumes with the drive attached to a Leopard system but okay to do what I like with the Leopard volume. And when running SL I'd expect the external SL volumes to be generally usable, but what about the Leopard volume? Would it be best to unmount and ignore it, or could it be safely copied with SD! if necessary?

Going back to my original question, assume that the volume currently being used for TM backups is instead intended for data to be sharable with any combination of Leopard/SL OS and PPC/Intel system I'm running. Let's say I erase and start using it under Leopard. Are there any conditions for later usage/copying on a SL system? And can I use/copy it under Leopard later?

If I recreated that "data" volume under SL could it be safely copied with Leopard? Or could that depend on the type of usage it gets while running under SL?

Sorry for the verbosity; hope it makes (some) sense. Before upgrading to SL I'm interested in having a better understanding of any volume interoperability issues with usage/copying under both Leopard and SL.

In general, I don't think it's a good idea to use 10.5 or later "touched" volumes from 10.4 or earlier. 10.5/10.6 is less critical, but generally once you've gone up an OS, it's a bad idea to work with that drive from a lesser version.

Networked drives are different because the file system is virtualized...

I believe you, and hate to belabor this, but do you have any specific "bad idea" examples (even if subtle, obscure, infrequent) that hopefully end the discussion? :)

Yup, what to anticipate and possible issues when using network filesystems is/are already clear (enough) to me.

Dave (and sjk)

Thanks for the thoughts; they pretty much mirror mine. Basically, I had already told him "don't do it," but was curious what others thought.

sjk, in his case, the "SL volume" was one in the truest sense, that is, a SL boot volume that he wished to clone, not merely one the chill had "touched."