In PowerFlex terminology, the Storage Data Server (SDS) acts as the "Target" for I/O operations.
Organize drives for storage pools (Option B): The SDS takes ownership of the local physical drives (NVMe/SSD/HDD) installed in the server. It aggregates these drives and contributes them to the Storage Pool. It handles the reading and writing of data blocks to this physical media.

Fault Sets are a logical subdivision within a Protection Domain used to increase availability (e.g., ensuring that the three copies of data reside in three different racks).
* Predefined Protection Domain (Option B): Fault Sets exist inside a Protection Domain. You cannot create a Fault Set floating in the void; it must be assigned to a parent Protection Domain.
* At least 3 nodes in the cluster (Option A): PowerFlex uses a mesh-mirroring architecture. To guarantee availability, the system generally requires a minimum of 3 Fault Sets (so that if one fails, the data can be rebuilt to the other two). Since a Fault Set must contain at least one node, this implies a minimum requirement of 3 nodes (one per Fault Set) to utilize the feature effectively.
Note on Option C: You typically define Fault Sets before creating Storage Pools or adding SDSs in a greenfield deployment. If Storage Pools already exist, converting to Fault Sets is complex/restricted, so
"Existing Storage Pool" is not a prerequisite for creating the Fault Set structure itself.

The Light Installation Agent (LIA) monitors node health and communicates with management components.

In Dell PowerFlex, Maintenance Mode is a critical operational state used primarily when a node requires software upgrades, firmware patches, or physical hardware replacement. When a Storage Data Server (SDS) requires maintenance, it cannot simply be powered down, as this would cause a rebuild of data to restore redundancy, placing immense stress on the cluster.
There are two types of maintenance modes:
Protected Maintenance Mode (PMM): This is the standard method for planned maintenance. The system identifies the data residing on the target node and makes a temporary copy (mesh- mirrors) of that data onto other nodes in the cluster before the node enters maintenance. This ensures that the cluster maintains full data protection (usually 2 copies) even while the node is offline.
Instant Maintenance Mode (IMM): This is used when time is critical, or the node is already offline.
It acknowledges the node is down but does not trigger a full rebuild immediately, relying on the remaining copy of data.
Therefore, the specific purpose is to allow administrators to perform necessary software upgrades or hardware swaps in a controlled manner that manages data integrity and prevents unnecessary
"storm" traffic from rebuilding data.

Verifying cluster health is the absolute prerequisite before attempting any upgrade or maintenance activity.
An upgrade involves taking nodes offline (rebooting) sequentially. When a node goes offline, the cluster relies on the remaining nodes to serve I/O and maintain data redundancy.
* If the cluster is already in a Degraded state (e.g., a drive is failed, or capacity is nearly full), taking a node offline could result in Data Unavailable (DU) or Data Loss (DL).
* PowerFlex Manager and the CLI provide "Pre-upgrade Health Checks." These checks validate:
* No active rebuilds or rebalances are running.
* All SDS and MDM components are connected and synchronized.
* There is sufficient spare capacity to handle a node failure or maintenance mode.
Resetting pools (Option A) creates data loss. Deduplication (Option C) is a feature choice, not an upgrade requirement.