PowerFlex upgrades require all nodes to be in Maintenance Mode. True. False.

The statement is false. PowerFlex is designed for high availability and resiliency, which includes the ability to perform non-disruptive upgrades (NDU). The standard upgrade procedure involves a rolling upgrade methodology where only one node (or a small subset of nodes) is placed into Maintenance Mode at a time. While the selected node is being upgraded, the rest of the cluster remains operational and continues to serve I/O. Once the upgrade on that node is complete and it is brought back online, the process is repeated for the next node until the entire cluster is upgraded. Requiring all nodes to be in Maintenance Mode simultaneously would cause a complete cluster outage, which is contrary to the design principles of PowerFlex.

The "True" option is incorrect because it describes a full-outage upgrade scenario. The core architecture of PowerFlex is built to avoid such service interruptions by allowing for sequential, rolling maintenance and upgrade operations on individual components while the system as a whole remains available.

1. Dell PowerFlex Upgrade Guide (Version 4.5.x): In the chapter "Upgrading PowerFlex," the procedure for upgrading Storage Data Server (SDS) components explicitly details a sequential process. The guide instructs the administrator to, "For each SDS, place the SDS in maintenance mode," perform the upgrade, and then "Exit maintenance mode." This step is repeated for each SDS in the system, confirming that only one is in maintenance at a time. (See Chapter: "Upgrading PowerFlex," Section: "Upgrading the SDS package").

2. Dell PowerFlex Administration Guide (Version 4.5.x): The guide explains the purpose of Maintenance Mode. It states, "You can place an SDS, device, SDC, or an entire fault set in maintenance mode to perform maintenance on it without incurring data rebalancing or rebuilds." This description implies that maintenance is performed on individual components while the rest of the system compensates, which is the foundation of a non-disruptive, rolling upgrade. (See Chapter: "Monitoring and management," Section: "Maintenance modes").