replacing external hard drive time machine

Time Machine will try to sync volumes and only backup files changed since the last snapshot if all goes well. If it’s a networked volume, you may have to double-click the disk image to open it and then double click Latest to get to the volumes. Drag that drive into the Terminal after the space. Drill down within the Backups.backupdb folder to the computer name then the Latest snapshot and then the drive name you want to associate.Drag the new or replaced Mac volume you want to associate with an old volume’s backup into the Terminal.Paste sudo tmutil associatedisk -a (the -a means to match and update all identical volumes, so you only need to do this once).Dragging also “escapes” (puts a backslash in front of) spaces and correctly represents other special characters so they’re read correctly in the Terminal.

In fact, it’s the best way to ensure you get the path exactly right without having to type it by hand. In the following examples, you’ll be dragging a folder from the Finder into the Terminal, which if you haven’t done before may seem like a strange mix.

Upgrade to a new Mac and migrate your old Mac’s data to it.

Swap a drive in your Mac and restore its contents.

Erase a drive and restore its contents.

For example, you might need to re-associate when you:

There are a lot of cases in which you use association, because association is based on a unique identifier for each drive that also changes when it’s erased. These are nested inside of “snapshot volumes,” and look something like this in their full path: Backups.backupdb/Glenn’s Mac/-123456/My Mac Drive. Volume association relates to each disk volume within a set. When you migrate from one Mac to another and want to connect the existing Time Machine backup, you inherit it, and thus transfer the computer identity in the Time Machine backup to your new Mac. Inheritance connects a Mac to a backup set, which Apple calls a “machine directory.” These are found in Backups.backupdb as the computer’s name. Apple offers two different types of Time Machine reconnections: inheritance and volume association.

Replacing external hard drive time machine