Two RAID1 mirrors are faster than three
Quoted 2 lines · Clemens Schwaighofer
Why three drives in a Raid1? Raid one is just mirror, or is the third drive like a "hot" replace drive if one of the others fail?
The goal is to get better (read) performance, as well as extra
redundancy. The system is supposed to balance reads among the available drives but in this case it breaks when there are more than two disks.
I have a "changes way too much code" patch that fixes this; guess
I should at least post it and see what happens...