Oracle Clusterware - What is the difference between Votedisk, quorum disk and quorum failure group?

Question

Some references say quorum disk and vote disk are the same, but "quorum disk" name was used in older versions. But Oracle 19c documentation still use both the names, so I think there is a difference. Also, when to use quorum failure group and what is it? documentation says:

A quorum failure group is a special type of failure group that does not contain user data. Quorum failure groups are used for storing Oracle ASM metadata. A quorum failure group may also contain voting files if those files are stored in a disk group that contains a quorum failure group. Additionally, Oracle ASM uses a quorum failure group to help determine if the disk group can be mounted in the event of the loss of one or more failure groups.

Ok, but, for example, we have a Oracle Clusterware running and there is no quorum failure group configured, so it seems it can be used or not. When to use it?

Answer 1

The QUORUM DISK can only contain the "voting file". But a voting file can reside in either QUORUM DISK or REGULAR DISK. And the voting file is called votedisk in the crsctl command ("Adding, Deleting, or Migrating Voting Files").

A quorum failgroup is a failgroup with quorum disk only. So if you place the voting file in a diskgroup with 2 regular disk + 1 quorum disk, and Oracle can have 3 copy of the voting file.