Which of the following considerations is important when planning the low-level design of a data center solution to ensure high availability?

High availability (HA) is a core principle in data center design focused on eliminating single points of failure (SPOFs) to maximize uptime. In the low-level design phase, which deals with the specific physical and logical components, a backup power source (e.g., Uninterruptible Power Supply - UPS, generators) is a fundamental requirement. It directly mitigates the risk of a complete site outage due to a failure in the primary utility power grid. Without redundant power, all other hardware and software HA features are rendered useless during a power loss, making it a critical consideration for a resilient infrastructure.

A. Software licensing agreements: This is a legal and financial consideration, not a technical design component that ensures system uptime or redundancy.
B. Network monitoring tools: These are operational tools used to detect and report on failures; they do not inherently provide the redundancy required for high availability.
D. Data encryption protocols: This is a security measure to ensure data confidentiality and integrity, which is separate from the system's operational uptime and availability.

1. Uptime Institute, "Data Center Site Infrastructure Tier Standard: Topology," (2018). This industry-standard document defines data center availability levels (Tiers). Tier II and higher explicitly require redundant capacity components, including UPS modules and engine generators, to ensure availability during a power outage. Section 3.0, "Tier II: Redundant Capacity Components," details the requirement for N+1 redundancy for power infrastructure.

2. HPE White Paper, "Planning for high availability with HPE Superdome Flex," (a00026236enw, March 2018). While product-specific, this document outlines universal HA principles. On page 4, under "The physical environment," it states, "High availability starts at the physical level... This includes redundant power supplies, redundant power distribution units (PDUs), and connections to independent power sources." This directly links backup power to the foundational layer of high availability design.

3. Barroso, L. A., Hölzle, U., & Ranganathan, P. (2018). The Datacenter as a Computer: An Introduction to the Design of Warehouse-Scale Machines (3rd ed.). Morgan & Claypool. Chapter 2, "Warehouse-Scale Computer Infrastructure," discusses power infrastructure extensively, noting that "To achieve high levels of availability, data centers use one or more levels of power backup, typically a combination of batteries (in the form of uninterruptible power supplies, or UPSs) and diesel-powered generators." This academic source confirms backup power as essential for data center availability.