The CELLCLI utility is a command line interface to Exadata that enables the execution of commands across multiple storage servers in parallel. It also has command-line history, so users can easily recall previously entered commands. Furthermore, the CELLCLI utility can be executed using the DCLI utility, which provides a convenient way to execute commands on multiple storage servers simultaneously.
However, CELLCLI does not require root privileges to create CELLDISKS and GRIDDISKS, and it cannot be executed on storage servers. This is because CELLCLI is used to manage the Exadata database machine from the database server [1]. For more information about CELLCLI, refer to the Oracle Exadata Database Machine X9M Implementation Essentials official text book and resources [1][2].

The Oracle Exadata Deployment Assistant Command Line Interface (OEDACU) supports a variety of configuration and lifecycle management tasks for Exadata systems, such as adding or removing nodes, resizing ASM disk groups, and managing Oracle Database home directories. However, it does not support lifecycle management for the Zero Data Loss Recovery Appliance (ZDLRA), as this device requires different management tools specific to its backup and recovery functions .

According to Oracle.com documents or resources, the four actions that you should take before proceeding with applying updates to your Exadata Database Machine are:
1. Consult My Oracle Support note 888828.1 to determine the current recommended Exadata software release123.
2. Check the Exadata Critical Issues My Oracle Support note 1270094.1 for any issues not added to the latest version of exachk453.
3. Run exachk and resolve only WARNINGS that you have not seen before3.
4. Run the appropriate patchmgr preqequisite check step for each component being updated3.

According to the Oracle documentation1, two statements that are true about enabling write-back flash cache are:
Write-back flash cache is on by default for High Capacity Storage Servers in High Redundancy configurations (A). This is because write-back flash cache provides better performance and reliability for data file writes than write-through flash cache.
Before write-back flash cache is enabled, you need to drop the Flash Cache first (D). This is because changing the flash cache mode requires recreating the flash cache with a different configuration.