Product: 
ccc6

Most tasks can be paused during the "Comparing and copying files" phase of the task. When a task is in a pausable phase, the Pause button will be enabled in CCC's main window, and the button with the "media pause" icon will be enabled in CCC's Dashboard application. Click the Pause button to temporarily pause the task. Click the Continue button to resume the task.

Paused tasks will resume automatically after 5 minutes

After 5 minutes, a paused task will automatically resume. You can change that period in CCC Settings > Advanced, although we recommend that you avoid setting that to very large values. Pausing a task will only pause the task's filesystem activity, it will not pause other filesystem activity on the source and destination volumes. The longer a task is paused, the greater chance there is of state inconsistencies arising between the filesystem and CCC's file copier.

Paused tasks are aborted when the computer is shut down. 

A paused task will not resume after a restart or shutdown.