Originally Posted by alwang17
So my friend's recently finished his build and is now looking to RAID his 6 WD Caviar Black 2TB hdd's. He's still debating whether or not to use RAID 5 or RAID 0+1. He finds 0+1 a bit more straightforward, but RAID 5 would give him more or less 10TB of space from what I understand (which isn't that much). However, he seems a bit wary of RAID 5, mostly because he doesn't understand it that well (neither do I). He's tried RAID 0+1 through the bundled software (Intel Rapid Sotrage Technology), but he can't select more than 4 drives for some reason. So right now, one of two things basically:
1. How safe is RAID 5 compared to 0+1 and a basic summary of it.
2. How to select 6 drives for RAID 0+1 through Intel Rapid Storage Technology.
Thanks in advance!
I'm not entirely sure on everything, and personally I've never used raid0+1.
Raid5 will allow one drive to die without any data loss. It's fairly straight forward too in terms of how much storage you'll have. Raid5 is essentially all the data minus one drive. So if you have three drives, it's going to be the capacity of only two of the drives. Or if you have four it'll be the capacity of three.
For general reference, say you have four 2TB drives.
In raid0 it's 8TB total capacity.
In raid1 it's 2TB total capacity.
In raid5 it's 6TB total capacity.
In raid 0+1 it's 4TB total capacity.
This calculator can help you if you don't want to read up on the differences between raid configurations: http://www.ibeast.com/content/tools/...c/RaidCalc.asp
The way raid 0+1 works is you have two raid0 arrays that are in a raid1. Raid1 is a mirror, where as raid0 has all the drives work together for increased performance to simplify the concept.
So as far as reliability goes, it's two arrays. Like this image:
If one drive dies, you'll be fine since it's mirrored. But as you can see, if two drives die on each side that have the same data stored, the array will fail.
In raid5 if any one drive fails, the array is fine, but if two drives fail the array fails. So raid0+1 is slightly more reliable.
I've never used Intel Rapid Storage Technology so I can't help much, but in theory I think you need to make two raid0 arrays then mirror them to complete a raid0+1 array. Again, I've never made a raid0+1 array so I can't be certain.