Acer TravelMate P645-M User Manual page 36

Note: Since the recovery backup requires at least 16 GB of storage after
formatting, it is recommended to use a USB drive with a capacity of 32 GB
or larger.
1. From Start, type 'Recovery' and then click Acer Recovery Management in
the list of apps.
2. Click Create Factory Default Backup. The Recovery Drive window opens.
Make sure Copy contents from the recovery partition to the recovery
drive is selected. This provides the most complete and safest recovery
backup.
3. Plug in the USB drive then click Next.
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