what is difference between raid 10 and 01 with explanation.

RAID 10 & RAID 01

RAID 10

• RAID 1+0 called as “stripe of mirrors”
• It requires minimum of 4 disks.
• Ex: The disks within the group are mirrored. But, the groups themselves are striped, It means within the group the data is (Raid-1) mirrored, across the groups the data is (Raid-0) striped.

For example to implementing the RAID 1 + 0 with 4 disks that will be in 2- groups, like Disk-1 and Disk 2 belongs to Group 1 and Disk-3 and Disk-4 belongs to Group 2.

Within the group the data is (Raid-1) mirrored, so the data on Disk-1 will be exactly same on Disk- 2 in Group-1. In the same way on Group-2 also.

So, block A written on Disk 1 will be mirrored on Disk 2, Like Block B written on Disk 3 will be mirrored on Disk 4.

Across the groups, the data is (Raid-0) striped, so this is why it is called “stripe of mirrors”.

                                                               RAID 01

• RAID 0+1 called as “mirror of stripes”
• It requires minimum of 3 disks. But in most cases this will be implemented as minimum of 4 disks.
• Ex: the disks within the groups are striped. But, the groups are mirrored.

For example to implementing the RAID 0 + 1 with 4 disks that will be in two groups, like Disk-1 and Disk-2 belongs to Group-1 and Disk-3 and Disk-4 belongs to Group-2.

Within the group, the data is striped. So block A is written to Disk-1 and block B to Disk-2. And Disk 1 mirrored to Disk3, Disk 2 mirrored to Disk 4.

Across the group, the data is mirrored. So the Group 1 and Group 2 will look exactly the same. This is why it is called “mirror of stripes

Main difference between RAID 10 and RAID 01

• Performance on both RAID 10 and RAID 01 will be the same and storage capacity on will be the same.
• The main difference is the fault tolerance level, RAID 01 fault tolerance is less.

• On RAID 0+1, since we have only two groups of RAID-0, if two disks (one in each group) fails; the entire RAID 01 will fail.

• In the above RAID 01 diagram, if Disk 1 and Disk 4 fail, both the groups will be down. So, the whole RAID 01 will fail.

• RAID 10 fault tolerances is more. On RAID 10, since there are many groups (as the individual group is only two disks), even if three disks fails (one in each group), the RAID 10 is still functional.

• In the above RAID 10 example, even if Disk 1, Disk 3, Disk 5 fails, the RAID 10 will still be functional.

• So, given a choice between RAID 10 and RAID 01, always choose RAID 10.