Creating multiple grid disks per cell disk allows you to create multiple pools of storage on the same Exadata Storage Server. The multiple grid disks can be assigned to separate
ASM diskgroups, which can be provisioned to different databases.
Note: Griddisk is a logical disk that can be created on a celldisk. In a standard Exadata deployment we create griddisks on hard disk based celldisks only. While it is possible to create griddisks on flashdisks, this is not a standard practice.
F: After you complete the cell configuration, you can perform the following optional steps on the storage cell:
References:https://docs.oracle.com/cd/E80920_01/SAGUG/SAGUG.pdf

The fastest database backup is achieved via InfiniBand.
RMAN does not back up directly to tape. However, it will integrate with media management software such as Oracle Secure Backup and utilize their capabilities to manage tape libraries.
Exadata Database Machine: The Database Machine contains the databases that need to be backed up. Oracle RMAN is the only mechanism to back up the databases that utilize Exadata Storage Servers as the storage. RMAN processes run on the database servers and interact with the Oracle Secure Backup (OSB) agent, which further interacts with the media management software and enables RMAN to communicate with the tape library.
References:
http://apprize.info/data/oracle_4/6.html

A: An Exadata snapshot database can be either a non-container database (non-CDB) or a container database (CDB). Creating an Exadata snapshot database of a CDB enables access to all of the pluggable databases in that container.
C: You can create two types of Exadata snapshots, depending on the current setup of your environment:
D: SPARSE disk group based database snapshots is functionality included in Exadata Storage Software. It requires Exadata Storage Software version 12.1.2.1.0 and Oracle Database 12c version 12.1.0.2 with bundle patch 5 or later. This feature is designed to work on native Exadata ASM storage disk groups. It uses ASM SPARSE grid disk based thin provisioning where snapshot databases created on a SPARSE disk group need only the space for changes plus some metadata, thereby enabling storage efficient snapshot databases.
References:
http://docs.oracle.com/cd/E80920_01/SAGUG/exadata-storage-server-snapshots.htm#SAGUG-GUID-E1D6EF45-36EF-40E3-A57E-F80B749E6122
http://www.oracle.com/technetwork/database/exadata/learnmore/exadata-database-copy-twp-2543083.pdf

Explanation/Reference:
A: To further accelerate OLTP workloads, the Exadata Smart Flash Cache also implements a special algorithm to reduce the latency of log write I/Os called Exadata Smart Flash Logging.
C: Use the Write-Back Flash Cache feature to leverage the Exadata Flash hardware and make Exadata Database Machine a faster system for Oracle Database Deployments.
D: Exadata X5-2 introduces Extreme Flash Storage Servers. Each Extreme Flash storage server contains eight 1.6 TB state-of-the-art PCI Flash drives. PCI flash delivers ultra-high performance by placing flash memory directly on the high speed PCI bus rather than behind slow disk controllers and directors.
References: http://www.oracle.com/technetwork/database/exadata/exadata-x5-2-ds-2406241.pdf
http://www.oracle.com/technetwork/articles/database/exadata-write-back-flash-2179184.html