Internal Drive
The ND2901 accepts 2.5 inch SATA hard drive(or SSD) used for laptop computer. The thickness of hard drive should be less than 9.5mm. Internal drive capacity is limited to 32TB, but the current maximum available hard drive is 2TB (as of Dec 2016). If your hard drive is less than 7mm thick, you can use ‘Spacer’.
* SSD capacity greater than 512GB is not recommended for the ND2901 due to limited battery power.

Recommended Internal Drive
Compatibility with the Seagate Samsung hard drive:
If your computer is base on USB 2.0, avoid using the Seagate hard drive on the early ND2901. Because the early ND2901 with Seagate hard drive may not detected at the computer with USB 2.0 port.Compatibility with SSD:
Be sure to connect the external battery for SSD capacity larger than 512GB (*).External Drive
An external USB device(External USB hard drive / USB memory card reader) can be connected to the ND2901 via the ‘USB Host’ slot of the ND2901. This allows users to make secondary copies to external USB drives without using a computer for additional data safety. Only 2.5-inch portable USB hard drives are supported. 3.5-inch desktop USB hard drives are not supported on the ND2901. External hard drives must be formatted using exFAT file system.
Connect the AC adapter to the ND2901 before connecting the USB device. The ND2901 does not detect USB devices without AC power connected.
4K sector size USB hard drive support
ND2901 does not support 4K sector size USB hard drive such as ‘Seagate Backup Plus Desk Top’ or ‘Western Digital My Book’. 3.5-inch desktop USB hard drives are not supported on the ND2901.
Maximum USB drive capacity 3TB
ND2901 does not support USB hard drive capacity greater than 3TB such as ‘Seagate Backup Plus 4TB / 5TB’ or ‘Seagate Backup Fast 3TB’.