More than that and you’re entering more complex and powerful business-class territory. Single-drive NAS devices don’t provide this data protection, and NAS boxes with more bays introduce more complex RAID configurations, such as RAID 5, RAID 6, or RAID 10, that require more planning and research to configure. As a result, your data remains safe and accessible even if a drive fails.

For example, a NAS with two 8 TB drives in RAID 1 still has 8 TB of total space available ( equivalent to about 300 Blu-rays), not 16 TB.

This setup gives you half the NAS’s actual amount of storage for files. For most home users, a two-drive NAS is just right, because it protects your data by mirroring the contents of one drive to the other (a configuration known as RAID 1, or a mirrored array). Two drive bays: Hundreds of NAS devices are available, and you can find models with one, two, four, eight, or more drive bays.