RoCE (RDMA over Converged Ethernet) and Persistent Memory are features that are supported by Oracle Linux. The minimum version of Oracle Linux required to support RoCE and Persistent Memory is Oracle Linux 7.9.
RoCE is a low-latency, high-bandwidth networking technology that enables fast data transfer between servers using converged Ethernet networks. It is supported by Oracle Linux 7.9 and later versions, which includes the necessary kernel modules and user-space libraries to enable RoCE.
Persistent Memory is a technology that allows data to be stored in non-volatile memory (NVM) devices, such as NVDIMMs (Non-Volatile Dual In-line Memory Modules), which can be accessed at near-DRAM speeds. Oracle Linux 7.9 and later versions include support for Persistent Memory, which includes kernel modules and user-space libraries to enable Persistent Memory.

Exadata storage realms using ASM-scoped security mode allows you to control which database can access which griddisks by creating realms at the ASM level, thereby allowing you to limit the access of each database to the griddisks that it needs to access. This is covered in section 3.15.2 of the Oracle Exadata Database Machine X9M Implementation Essentials Official Text Book and Resources [1].
Exadata storage realms using database-scoped security mode allows you to control which database can access which griddisks by creating realms at the database level [1], thereby allowing you to limit the access of each database to the griddisks that it needs to access. This is covered in section 3.15.3 of the Oracle Exadata Database Machine X9M Implementation Essentials Official Text Book and Resources [2].
[1] https://docs.oracle.com/en/engineered-systems/exadata-database-machine/x9m/exad-implementing-database-machine-x9m.pdf [2] https://docs.oracle.com/en/engineered-systems/exadata-database-machine/x9m/exad-implementing-database-machine-x9m.pdf

Your customer needs to ensure that their data is available on the Exadata machine during updates. The customer wants to be able to update one server at a time but still be protected against single-node server failure. This means that they need a redundancy level that can tolerate at least one disk failure without losing data availability or performance. Therefore, the best option for them is normal redundancy . Normal redundancy provides two-way mirroring by default, which means that each data extent has a primary copy and a mirror copy on different disks in different failure groups1. A failure group is a subset of disks within a disk group that are likely to fail at the same time due to common dependencies2. On Exadata Database Machine , each Storage Server is considered as a failure group by default2. This means that if one Storage Server fails or needs to be updated , the data on its disks can still be accessed from another Storage Server that has the mirror copies of the same data extents2. Therefore, normal redundancy ensures data availability and performance during updates or single-node server failures.
https://docs.oracle.com/en/engineered-systems/exadata-database-machine/sagug/exadata-administering-asm.html

1. dbmcli -e "LIST METRICHISTORY WHERE name LIKE 'DS_.*'" is valid command and it is used to list the historical values for metrics where the name starts with "DS_."
2. dbmcli -e "LIST METRICCURRENT WHERE name = 'DS_TEMP' " is valid command and it is used to list the current value of the metric named "DS_TEMP"
3. dbmcli -e "LIST IBPORT DETAIL" is valid command and it is used to list the InfiniBand ports and details of the Exadata X9M.
"dbmcli" is a command-line tool that is used to manage and monitor the Exadata Database Machine. It allows you to perform various tasks such as managing the database, storage, and network components, and monitoring the performance and health of the machine. The command "dbmcli -e "LIST ALERTHISTORY WHERE agelnMinutes < 15" is not a valid command, it is not supported on Exadata X9M.