# Creating a bootable backup

It can be useful for a backup of an entire drive to be bootable, so that if your main system goes down, you can resume nearly without interruption from the backup copy. In the old days of Mac OS 9 and before, this was a relatively straightforward task, but the UNIX underpinnings of Mac OS X makes it a slightly more involved procedure these days.

Synk will automatically take care of most of the details involved whenever it is safe for it to automatically do so, but there are several settings you will need to set yourself because it would be unsafe for Synk to do so by itself. I feel it is a better approach to leave this choice and power in the hands of the user than to have Synk guess when you're trying to do a bootable backup, guess wrong, and mess up a different backup.

## To make a bootable backup, the following conditions must hold:

- You should select the entire disk as your backup source. The source path should show "/" only.
- Synk must be set to run as root through the Preferences pane. There should be red text at the bottom of your document window saying "RUNNING AS ROOT." (more info)
- In the Settings tab, alias/symbolic link handling must be set to "treat as ordinary file,", and "always resolve-top level aliases/links" must be unchecked.
- (more info)
- "Ignore ownership on this volume" must not be set for either drive. You can see this setting in the Finder by choosing "Get Info." This is not a Synk setting, but is needed for a successful bootable backup.

Note that you should always confirm the bootability of the backup before something goes wrong and you need it. The new UNIX underpinnings of Mac OS X can be very picky, and if any of the above conditions do not hold when you do your backup, the result will not be bootable, so take care when doing your setup. If you end up with a non-bootable drive, reformat the target drive, fix the above settings, and try again.

This section of the help files will be updated in new versions as Mac OS X changes and should always have the most up-to-date requirements, but system updates between this version of Synk's release and when you run the backup may change matters. It is always a good policy to check your backups regularly, regardless of what method you use or whether you have special requirements like it being bootable.