RAID 5 of two disks

By Geek -
The common wisdom says that RAID 5 requires a minimum of three disks.
If one thinks of it, it is not true.
You can create a RAID 5 of two disks. With even parity, the array becomes a mirror (RAID 1), and with odd parity (although nobody ever uses that), becomes a RAID 4 of two disks.

And yes, the same applies to a RAID 4 of two disks.

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