In an Automatic Storage Management (ASM) environment, failure groups are used to provide redundancy for the storage disks. Failure groups are used to group together a set of disks and ensure that no two copies of the same data are stored on the same physical disk or storage server. This way, if a disk or storage server fails, the data can still be accessed from the other copy.
For example, if the disks in a failure group are mirrored, one copy of the data is stored on one set of disks, and the other copy is stored on another set of disks. This way, if a disk or storage server fails, the data can still be accessed from the other copy.
ASM failure groups also provide the option to spread the data across different storage servers, this way, even if a storage server fails, data can still be accessed from the other storage servers in the group. This will improve the availability of the data.

Persistent Memory Commit Accelerator reduces redo log write latency by using Persistent Memory and RDMA before flushing to Flash then disk. This helps to further reduce redo log write latency by utilizing the speed and low latency of Persistent Memory, along with the Remote Direct Memory Access (RDMA) protocol, to commit changes to disk faster. This allows the system to quickly commit changes to disk, resulting in improved performance and reduced latency.

1. Querying VSSYSTEM_EVENTS for the event 'cell physical IO interconnect bytes returned by smart scan' will not be appropriate for monitoring the access on a particular table. The V$SYSTEM_EVENT view is used to monitor system-wide performance statistics, not specific table access. C. Querying v$SYSTAT for the statistic 'cell smart table scan' will not be appropriate for monitoring the access on a particular table as well. The v$SYSTAT view contains system-wide performance statistics, not specific table access.

According to Oracle's documentation1, the customer options for hosting the Platinum Services Advanced Support Gateway are:
Provide individual x86 64-Bit gateway hardware1
Purchase the recommended x86 64-Bit gateway hardware from Oracle1
Install on Oracle Database Appliance2

Once the physical disk has been replaced, you will need to create a new celldisk and griddisks on the replaced physical disk. After the griddisks have been dropped from the associated ASM diskgroups, you can then add the griddisks back into the ASM diskgroup they used to be a member of and rebalance the data on the effected griddisks. Finally, you should verify that the griddisks located on the physical disk have been successfully dropped from the associated ASM diskgroups.