PDA

View Full Version : Drive not Bootable After User Backup


tomjwright
06-09-2009, 05:38 PM
When I backup "all files" from the internal drive onto an external drive, the cloned drive is bootable. This is true whether I do a complete backup or a Smart Update.

However, if I subsequently backup "user files" using Smart Update, the previously bootable clone is no longer bootable -- that is, it does not show in the window of bootable options when I view System Preferences > Startup Disk.

The SuperDuper! window after the "user files" backup process is complete lists, as the last action, making the clone bootable.

This behavior is consistent. I'm running OS 10.5.7.

Is this normal behavior?

chris_johnsen
06-10-2009, 02:32 AM
This is normal. The confusion is over the way that the "user files" option works.

It looks at the source volume, and only 'selects' files from /Users. This selection mechanism is controlled by the backup script: "all files" vs. "user files" vs. "sandbox", etc.. When writing files to the destination volume, if a file is on the destination but has not been selected from the source volume, it will be deleted from the destination. So, even if the file exists on the source volume, if it is not selected for copying, it will be deleted from the target volume (if it exists there).

What this means is that when you run a "user files" backup to a volume that previously contained an "all files" backup, all the files except for your user files are deleted (important stuff like the OS!).

The "make it bootable" step at the end is a technical detail involving the bless command. It is there because if you just make a plain file-by-file copy of a bootable volume to another volume, that new volume will not be bootable until it is blessed as bootable. This involves putting some data in a special place on the disk (somewhere outside the normal filesystem) where the machine's boot firmware (OpenFirmware or EFI, like the BIOS on old(?) DOS/Windows machines) can find it. If you used DOS, bless is analogous to the SYS DOS command.

If you want a backup to be actually bootable, you always need to use "all files".

dnanian
06-10-2009, 05:52 AM
Chris is right here. It is "normal" that it did what it did: what's not normal is your use. This specific case is covered in the User's Guide, in fact... as he says, always use "Backup - all files" with "Smart Update".

tomjwright
06-10-2009, 01:58 PM
Thanks to both of you for responding. I should have read the User Guide more carefully. My reason for trying to copy only the user files is that I have a desktop that I use regularly and a laptop that I use only occasionally. The two computers don't have all the same applications installed (a personal choice). I had hoped that by using the User Files backup (from a drive that duplicates the internal drive on the desktop) onto the laptop I would be able to quickly update all the user files on the laptop without disturbing the other files.

I understand now that this was wishful thinking on my part. I'll look into using Time Machine or the brute force method of replacing the user files on the laptop with those on the desktop via the Finder.

Thanks again.

dnanian
06-10-2009, 02:56 PM
I'm pretty sure Time Machine isn't going to be able to do this either, Tom. Neither TM nor SD! are designed to 'sync' two Macs.

tomjwright
06-10-2009, 10:21 PM
Yep, Dave, I've come to the same conclusion. The Finder copy method seems to be the only surefire way to accomplish what I want to do.

It sure would be nice if SuperDuper! could replace only those files in a designated folder (say a given users folder) that are different from the source folder without changing any other files and then leave the target disk in a bootable condition (assuming it was bootable before the new action). Is there some technical reason why that is impossible in a future version?

dnanian
06-11-2009, 06:49 AM
No, there's no technical reason: it's a 'focus' reason. We're not trying to make SD! do everything it "can" do -- just everything it "should" do, given its mission.