If you need to upgrade or replace your Time Machine drive, you can do so without starting your backups over again.
Affected users may not be able to restore or migrate from recent backup instances. See if you're one of them.
If you have a file or two you wish to remove from your Time Machine backups, you can do so right in the Time Machine interface.
The online backup startup will release an app in coming weeks to let iOS users see and share files, including versions up to 30 days old.