Quorum disks enable users to leverage disks on database servers to achieve highest redundancy in quarter or eight rack configurations. Since Quorum Disk is a new concept related to Oracle RAC voting disks, I like to begin with a brief description for Voting Disk. Oracle Real Application cluster is consist of 1 or more nodes and it is imperative for cluster to know its member any point in time. That where voting disks are used to keep track of active members in any given cluster so it can perform certain task like load balancing or recourse failover. Voting disk contain static and dynamic data, dynamic data logs heart beat activity of a cluster. Loss of voting disk can cause RAC to evict nodes, since it cannot communicate or see other nodes in a cluster.
Now Exadata :
In earlier releases, when HIGH redundancy was deployed, the voting disk for the cluster was created on a disk group with NORMAL redundancy. Starting with Exadata Software release 18.104.22.168.0, the voting disks can reside in a high redundancy disk group even with less than 5 storage cell using Quorum disk from Database servers. This can be achieve thought OEDA utility when deploying Exadata or can added later using Quorum Disk Manager Utility as long as you meet following software and hardware requirements.
Minimum software requirements
- Oracle Exadata Storage Server Software release 22.214.171.124.0
- Grid Infrastructure release 126.96.36.199.160119 with these patches: 22722476 and 22682752; or Grid Infrastructure release 188.8.131.52.160419 or later
- Patch 23200778 for all Database homes
Minimum Hardware Requirements
- The Exadata rack has fewer than five storage servers.
- The Exadata rack has at least two database nodes.
- The Exadata rack has at least one high redundancy disk group.