Can someone laymens term a Raid 50

[Tomsta]

Watching Linus video on when wannick server died i am struggling to get my head round the implmentation of RAID 50. I understand RAID 5 and 0 seperatley just cant quite understand how they work together

 

Can someone laymens term it for me? Also why would loosing 3 drives in one array dooms the entire setup? 

[nox_]

https://searchstorage.techtarget.com/definition/RAID-50-RAID-50

[leadeater]

RAID 5 offers a single disk of redundancy, which you already know. So RAID 50 is multiple RAID 5 arrays which are then added in to a RAID 0 array where these RAID 5 arrays are the member devices of that array. This is known as nested RAID.

 

So if you have 8 disks you take 4 of them and put them in a RAID 5 array, then you put the other 4 remaining disks in to a RAID 5 array. Now you have two independent RAID 5 arrays. Next you create a RAID 0 array and place both RAID 5 arrays in to this array, you now have a RAID 50 array.

 

A RAID 50 array can be destroyed with as few disks as 2 failing, 2 disks from the same RAID 5 array in the RAID 50 array. Since the upper layer is RAID 0 this offers no redundancy so it requires that only a single sub array is lost/offline for the entire RAID 50 to be destroyed.