Exadata Secure RDMA Fabric isolation is a feature that allows you to use virtualization on the X9M-2 platform while maintaining security and isolation between multiple tenants or VM clusters. Secure Fabric isolation works by creating a dedicated network partition and VLAN ID for each Database VM cluster, which is used for cluster networking between the database servers in the VM Cluster. This ensures that the network traffic of each VM cluster is isolated from the others, and it prevents unauthorized access to the data or resources of other VM clusters. Secure Fabric isolation can also be used for other purposes such as client networking, Data Guard traffic, but it's mainly used to provide security and isolation between multiple tenants or VM clusters.

According to Oracle's documentation12, some of the statements that are true about applying updates on Exadata systems are:
Failed storage server updates are automatically rolled back to a previous release1.
When running a "yum update" for a new Exadata release, all other repositories should be disabled1.

The Exadata X9M-2 Extended (XT) Storage Server does not include any Persistent Memory (PMEM) DIMMs. The XT server configuration primarily serves as a cost-effective archival storage option and lacks the performance features available in the HC (High Capacity) and EF (Extreme Flash) storage servers. This configuration does not include Persistent Memory, which is leveraged in other models for accelerating OLTP workloads and providing extremely low-latency data access.

Failure groups provide redundancy in Oracle Exadata Database Machine X9M by ensuring that mirror copies of the data are written to different storage servers [1][2]. This prevents the potential for mirror copies to be written to the same server, which would cause a data loss if that server were to experience a physical disk failure. Furthermore, failure groups help to ensure that the ASM Flex instances are enabled on a maximum of two database servers or VMs per cluster, providing an extra layer of data protection. Additionally, Extended Redundancy mirrors data across data centers, providing the highest levels of data protection. Reference: Oracle Exadata Database Machine X9M Implementation Essentials [1][2], Chapter 5: Configuring Oracle ASM.

According to Oracle's documentation1, the client network on Exadata X9M-2 Database Server is used for client access to the database servers using Single Client Access Name (SCAN) and Oracle RAC Virtual IP (VIP) addresses. To verify that the client network is available via both client switches, you can use the command:
cat /proc/net/bonding/bondeth0
This command displays information about the bondeth0 interface, which is used for the client network on Exadata X9M-2 Database Server2. You can check if both interfaces (eth0 and eth1) are active and connected to different switches3.