Infrastructure Maintenance Fails During Cell Update Due to Missing Quorum Disk Device Links in a VM (Doc ID 2978693.1)

Last updated on NOVEMBER 26, 2023

Applies to:

Symptoms

Exadata uses quorum disks to maintain redundancy and high availability for critical Oracle ASM metadata and clusterware voting files on small Exadata systems. A quorum failure group is a special type of failure group that does not contain user data. A quorum failure group contains only a quorum disk, which may be used to store copies of the PST(ASM Partner Status Table) and clusterware voting files. Quorum failure groups (and quorum disks) are only required on Exadata systems that do not contain enough storage servers to provide the required minimum number of failure groups. The most common requirement for quorum failure groups (and quorum disks) is on Exadata systems with high redundancy ASM disk groups and fewer than 5 Exadata storage servers.

1.) If this issue is encountered, an Exadata System with quorum disk(s) configured, ls -l /dev/exadata_quorum/  does not list all expected quorum device soft links.

    For example, on an Exadata system with three CELLs, and two high redundancy disk groups, on each node,  four devices should be present as below. If the output does not show one or more expected devices, that is one of the symptoms of this issue.    

Expected output: (example from Exadata system with three CELLs and the issue is not encountered)

POTENTIAL IMPACTS:
    Exadata monthly security cell patching may fail to bring back the disks online and this can cause performance issues due to reduced IO capacity.
    Clusterware restart or ASM diskgroup unmount/mount operations may fail due to the insufficient number of PST blocks.
    Clusterware CSSD may fail and reboot the node if the number of voting disks available falls below the minimum required.

Cause

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