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I am using Snow Leopard in macbookpro unibody 15p. Usually did time machine backups. Now I thought about downgrading to Leopard given my problems with Leopard. I erased the Disk, and booted in Leopard when installed. I expected I could use my Snow Lopeard time machine backup here but I get an error message, saying that in Leopard one can not migrate from newer versions.

Do you know a workaround for this so I can get the data?

At the moment I will probably copy all SL TM backup to the harddisk and copy files.

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migrated from Feb 27 '10 at 17:26

This question came from our site for professional and enthusiast programmers.

You'll probably get better responses at Superuser. – Xorlev Feb 27 '10 at 17:16
What was the nature of your problems with Snow Leopard? Are they insurmountable - it might be easier just to upgrade again. – alimack Mar 1 '10 at 14:58

You may get lucky, but the idea of moving files that were previously managed by Snow Leopard back to Leopard is fraught with problems. In particular, the transparent file compression that Snow Leopard can do is not readable in Leopard (see John Siracusa's Snow Leopard review under “Installation footprint”).

I am not sure whether Snow Leopard would automatically upgrade its Time Machine volume to use compression or not. If so, you might have to use a Snow Leopard machine to read the data.

Besides low level things like transparent compression, there will also be application-level compatibility issues with any applications that have to be downgraded due to the OS downgrade. Obvious the built-in apps are affected, but other apps might also be affected if you were using latest versions that are not backwards compatible with Leopard.

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I'm pretty sure anything using transparent compression is a file you don't want to restore anyway. – Abhi Beckert Aug 12 '12 at 23:33

I think the workaround you ask for is actually what you're already thinking--copying the data to a 10.6 system and then transferring it to the 10.5 one. The process of transferring gets rid of the HFS compression. If you want a faster and more flexible method of copying from the backup volume than using Apple's own Time, it's always possible to do a "manual" copy by disabling the ACL on the drive. The compression is only filesystem-level, so when those files are moved to the 10.5 system they won't be recompressed on the target drive.

However, I would strongly suggest figuring out your Snow Leopard problems--it's a much more stable and consistent system than 10.5. Your 10.6 install DVD can actually be used to do a clean system install even if it was marketed as an upgrade. I'd try that.

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Holding down Option while clicking the Time Machine icon, will change "Enter Time Machine" into "Browse Other Time Machine Disks". I guess that makes it easier to restore just the documents you need, after a clean install of Leopard (without any migration during the installation).

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Make a second backup (with disk utility or carbon copy cloner) of your boot partition, then erase it. Do not skip this step! You need at least two copies of the data at all time, which means making a second backup before deleting the originals.

Install a blank copy of Leopard onto the empty partition, ignore any prompts to restore from a time machine backup.

On your time machine backup disk, open up the backups.backupdb file, open the directory named after your computer, then open the "latest" folder. All of your data is in there, you can copy apps and files and so on over.

Some apps, such as microsoft office, are better off installed from scratch instead of restoring a backup.

Some of your data is in "Library" directories. Copying this data over to the new system is a bit risky, I would only copy the stuff you know you need (for example, keychain and emails and textmate settings). Try to avoid restoring as much of this as possible ... nobody ever tests going downgrading software properly, you will run into issues if you restore it.

If something goes wrong with the system while messing around with your ~/Library folder, just delete it and log out/in again. A new one will be created for you with default settings, and you can start restoring from backups again - this time skip the one that caused problems.

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