Linux raid10 on 2 disks

Solution 1:

Well, as the second link you provide suggests there's no certainty that mirrored stripes are on separate disks - so to be honest the concept is worthless and dangerous.

Solution 2:

A 2-disk RAID10 is useful for one, and only one, kind of access: single-threaded, sequential, large-block IO read requests. In that specific scenario, it behave similarly to a RAID0 setup.

For all other uses, (random read/writes, multithreaded access, ecc) a simple, cleaner RAID1 array is better due to significantly less head seeks (which are very expensive on a mechanical drive).

Solution 3:

While not a comment about security, Pat Reagan explains his choice to use RAID 10 with 2 disks was guided by his expectation to grow the array in the future, as growing a RAID 10 is much simpler than later converting a RAID 1 to a RAID 10 or 6.

Also worth noting is that mdadm v3.3+ allows you to grow a RAID 10, where earlier versions do not.

A comment in this SO answer mentions RAID10 can only be grown with near2, not far2. I haven't verified this.