mdadm –detail used device size | Senior Full Stack Developer, Coder, C#, Java, Linux, Network, PHP, Cloud

For RAID0, "Used Dev Size" does not exist.
For RAID1, "Used Dev Size" equals to half of total disks' size.
For RAID5, "Used Dev Size" equals to size that are used for parity.

For RAID0, "Used Dev Size" does not exist.

For RAID1, "Used Dev Size" equals to half of total disks' size.

For RAID5, "Used Dev Size" equals to size that are used for parity.

TESTED !