5big thunderbolt 2 and raid5/6

[eish2306]

the 5 big has 5 hard drives 2 4 or 6tb each so 10 20 or 30tb in total

I have just had a drive die and have decided to invest some money in storage - I have some media, work back up, personal photos and itunes

I thankfully only lost my iTunes, some recent media and some personal photos - I have recovered most of my iTunes from various devices - thank god for iPod classics - just not some rare cast albums and cds - but I do have them in storage - well most of them - and have some photos back via iCloud

(I never saw the point in having them all in iCloud - I was like why waste cloud storage when iOS 8 arrives) I should also be able to get some back from Facebook and diary/memory apps - but I want to make sure I am protected in the future.

If I understand I can make the 5big act as one giant hard drive which is device agnostic (the Hardware RAID 5/6 with hot-swappable disks feature) so swapping between mac pro and mac book or new mac pro in the future (5k daydreams) - which I will probably split up for simplicity.

So my question is

If I have the 20tb 5 big so 4tb hdds in each - and I use Raid 6 set up how many tb will I have overall for storage?
and
If I have the 10tb 5 big so 2tb hdds in each - and I use Raid 5 set up how many tb will I have overall for storage?

or any combination - if I understand correctly - I am tired atm having being in damage control mode all day and last night - that raid 5 means 1 drive is redundant and raid 6 means 2 are so if the drives are 6tb I get
6x4 so 24tb with RAID 5 and
6x3 so 18tb with RAID 6

If I am correct which one is best in this case (i.e. I won't loose any data should one drive fail) - if not please correct me

 

[matreya]

If I have the 20tb 5 big so 4tb hdds in each - and I use Raid 6 set up how many tb will I have overall for storage?
and
If I have the 10tb 5 big so 2tb hdds in each - and I use Raid 5 set up how many tb will I have overall for storage?

or any combination - if I understand correctly - I am tired atm having being in damage control mode all day and last night - that raid 5 means 1 drive is redundant and raid 6 means 2 are so if the drives are 6tb I get
6x4 so 24tb with RAID 5 and
6x3 so 18tb with RAID 6

If I am correct which one is best in this case (i.e. I won't loose any data should one drive fail) - if not please correct me

With RAID5, it only uses 4 drives, with the 5th drive available as a quick swap if one of the RAID5 set of 4 drives fails. So with RAID5 you get 3/5 of the total of any 5 big as overall storage. 10TB->6TB, 20->12TB, 30->18TB

With RAID6, it again will use 4 drives, but keep 2 of them for redundancy, so you get 2/5 of the total of a 5big... plus the 5th drive is a spare..
10TB->4TB, 20->8TB, 30->12TB

 

[g4cube]

With RAID5, it only uses 4 drives, with the 5th drive available as a quick swap if one of the RAID5 set of 4 drives fails. So with RAID5 you get 3/5 of the total of any 5 big as overall storage. 10TB->6TB, 20->12TB, 30->18TB

With RAID6, it again will use 4 drives, but keep 2 of them for redundancy, so you get 2/5 of the total of a 5big... plus the 5th drive is a spare..
10TB->4TB, 20->8TB, 30->12TB

Totally configurable by the user: you can dedicate all 5 drives to a RAID-5 or a RAID-6 array for the most capacity.

Alternative is to use only 4 drives for the RAID-5 or RAID-6 array, and keep the 5th drive as a hot spare.

RAID-6 is preferred over RAID-5, as it continues to provide protection after one of the drives fails and rebuild is underway. Additional parity protects the array from 2nd drive failure during rebuild.

In a RAID-5 array, if a drive fails, performance is degraded during the rebuild after spare drive is added back to array, but there is no parity protection of the array until after the rebuild completes.

Just remember it this way, RAID-5 protects against single drive failure of the array, while RAID-6 protects against 2-drive failure in an array.

There are many, many references about RAID arrays that go into much more detail.