Oracle ASM supports fixed partnership for disks. Oracle ASM performs splitting and mirroring of data across all disk partners. All Oracle Database Appliance single-node systems support 8 disks partnership provided there are enough disks to support it. If the number of NVMe disks are less than eight then all disks partner among themselves.
NVMe disks are populated across the PCI switch card for equal distribution of IO bandwidth across IO sub-systems. QRM1 and QRM2 have 1GB partitioned carved out from the operating system disk. They are used as DATA and RECO quorum disk respectively in Oracle ASM. These disk are used if the number of NVMe disks is less than 5. They are used for storing PST and voting files. They are used when a disk with voting file or PST get lost. Their content helps to decide the majority without which the Oracle ASM disk group cannot be mounted.
The disk partnership information is part of the asmappl.config file.
The disk partnership on Oracle Database Appliance single-node system is as follows:
DATA Disk S0 partners with S2, S3, S4, S5, S8, S9, S10, S11
RECO Disk S0 partners with S2, S3, S4, S5, S8, S9, S10, S11
If disk in slot 0 is lost for any reason, Oracle ASM restores and rebalances data on lost disks among the partners of lost disk.