Quorum disk configuration

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A quorum disk is an MDisk or a managed drive that contains a reserved area that is used exclusively for system management. A system automatically assigns quorum disk candidates. When you add new storage to a system or remove existing storage, however, it is a good practice to review the quorum disk assignments.

It is possible for a system to split into two groups where each group contains half the original number of nodes in the system. A quorum device determines which group of nodes stops operating and processing I/O requests. In this tie-break situation, the first group of nodes that accesses the quorum device is marked as the owner of the quorum device and as a result continues to operate as the system, handling all I/O requests. If the other group of nodes cannot access the quorum device or finds that the quorum device is owned by another group of nodes, it stops operating as the system and does not handle I/O requests.

A system can have only one active quorum device that is used for a tie-break situation. However, the system uses up to three quorum devices to record a backup of system configuration data to be used in the event of a disaster. The system automatically selects one quorum device to be the active quorum device. The active quorum device can be specified by using the chquorum command-line interface (CLI) command with the active parameter. To view the current quorum device status, use the lsquorum command.

The other quorum devices provide redundancy if the active quorum device fails before a system is partitioned. To avoid the possibility of losing all the quorum devices with a single failure, assign quorum disk candidates on multiple storage systems or run IP quorum applications on multiple servers.

Note: Mirrored volumes can be taken offline if no quorum disk is available. The synchronization status for mirrored volumes is recorded on the quorum disk.