Database Software

I have query that why voting disk are always recommended in odd number.

The voting disk must reside on a shared disk(s) that is accessible by all of the nodes in the cluster. For high availability, Oracle recommends that you have multiple voting disks. Oracle Clusterware can be configured to maintain multiple voting disks (multiplexing) but you must have an odd number of voting disks, such as three, five, and so on. Oracle Clusterware supports a maximum of 32 voting disks. If you define a single voting disk, then you should use external mirroring to provide redundancy.

A node must be able to access more than half of the voting disks at any time. For example, if you have five voting disks configured, then a node must be able to access at least three of the voting disks at any time. If a node cannot access the minimum required number of voting disks it is evicted, or removed, from the cluster.

Here I have a table :
Total no of vdisk (n) Minimum vdisk required by nodes (>n/2) No of vdisk can be failed simultaneously
1 1 0
2 1 1
3 2 1
4 2 2
5 3 2
6 3 3
7 4 3
Here, it is clear that it doesn't matter that the vdisk 4 or 5, the No of vdisk can be failed simultaneously would be 2. So, not sure that why odd number of voting disks are recommended.

Kindly suggest.

Regards,
Dheeraj Vaish