The Quorum Disk Manager utility is a new feature in Oracle SuperCluster release 2.3.
Using this utility, you can create an iSCSI quorum disk on two of the database domains and store a voting file on those two quorum disks. These two additional voting files are used to meet the minimum requirement of five voting files for a high redundancy disk group. This feature is only applicable to Oracle SuperCluster systems that meet the following requirements:
The Oracle SuperCluster rack has fewer than five storage servers
The Oracle SuperCluster rack has at least two database domains
You will have at least one high redundancy disk group
This feature allows for the voting files to be stored in a high redundancy disk group on Oracle SuperCluster racks with fewer than five storage servers by creating two extra failure groups.
Without this feature, on Oracle SuperCluster racks with fewer than five storage servers, voting files are stored in a normal redundancy disk group. This makes the Grid Infrastructure vulnerable to a double partner storage server failure that results in the loss of the voting file quorum, which then leads to a complete cluster and database outage. Refer to My Oracle Support note 1339373.1 to restart the clusterware and databases in this situation.
The iSCSI quorum disks are stored inside the ZFS storage appliance and are available for each domain, so they have the benefit of high availability. Systems with three Exadata storage servers require two quorum devices for high redundancy.
In SuperCluster M8 and SuperCluster M7, the two ZFS storage controllers are set in an active-active configuration. On an active-active ZFS storage appliance system in a correctly-configured SuperCluster M8 and SuperCluster M7 (one that has been set up using best practices), one iSCSI quorum disk device will be created on each ZFS storage controller. During controller failover, the quorum device associated with the failed controller will temporarily become unavailable.
In SuperCluster T4-4, T5-8 and M6-32, the two ZFS storage controllers are set in an active-passive configuration. On an active-passive ZFS storage appliance system, both iSCSI quorum disk devices will be created in the same pool. During controller failover, both quorum devices will temporarily become unavailable.
The Quorum Disk Manager utility (quorumdiskmgr) is used to create and manage all the necessary components for implementing this feature, including the iSCSI configuration, the iSCSI targets, the iSCSI LUNs, and the iSCSI devices. For more information on the Quorum Disk Manager utility, see Quorum Disk Manager Reference.
This feature is applicable to Oracle RAC clusters with Database I/O Domains, dedicated Database Domains, and zones on dedicated Database Domains or Database I/O Domains. For Oracle RAC clusters with zones on dedicated Database Domains or Database I/O Domains, the quorum disk devices are created and managed from its corresponding global zone.