amúgy az a cikk teljesen f*cked up...
pl.:
Moving beyond the question of individual disk reliability,
btrfs-raid1can only tolerate a single disk failure, no matter how large the total array is. The remaining copies of the blocks that were on a lost disk are distributed throughout the entire array—so losing any second disk loses you the array along with it. (This is in contrast to RAID10 arrays, which can survive any number of disk failures as long as no two are from the same mirror pair.)
az előbb próbáltam ki 4 diszkkel, ebből kettőt kiszedtem (degraded-ben, nyilván), még fileokat is másoltam rá, utána visszaraktam a hiányzókat... és a scrub ügyesen besyncelte őket...