title: Difference between (in fault tolerance) RAID 10 and RAID 01 (RAID 0+1 vs RAID 1+0 )?
body: <p>RAID 10 seems to me as a permutation RAID 01. Then how can it be more fault tolerant than RAID 01?</p>
  
  <p>I see the description here but it explains by dividing disks into groups and one disk if fails in each group there is no data loss in raid 10 but there can be data loss in raid 01. But what do these groups physically mean? Aren't there basically just 6 disks in the example in the given link?</p>
  
  <p><a href="http://www.thegeekstuff.com/2011/10/raid10-vs-raid01/" rel="nofollow">http://www.thegeekstuff.com/2011/10/raid10-vs-raid01/</a></p>
  
  <p>I see this link <a href="http://www.tomshardware.com/forum/43220-32-raid-raid0-raid10-explained#" rel="nofollow">http://www.tomshardware.com/forum/43220-32-raid-raid0-raid10-explained#</a>.
  where the discussion ends concluding that in case of RAID 01 if any disk fails in one of the array/group consisting of stripes, all the disks become inaccessible by the controller. But for RAID 10 the controller can access the good disks of the array/group consisting of mirrored disks. Why is it so? When there is a read/write request why can't in case of RAID 01 it just access the good drives in array/group 1 and the drive which failed be accessed into the other group/array which is the mirror of group/array1?</p>