Storage Architecture and Technology Principles

Selection criteria should include legal requirements (B), public specifications (C) for interoperability, organizational standards compliance (D), and privacy safeguards (E). 'Should be compliant' (A) is too vague: compliant with what? It's not meaningful criteria without specifying what standard or requirement.

Principles should be understandable (B), robust (C), complete (D), and consistent (E). They should NOT be complex (A): good principles are simple, clear, and concise. Complexity makes principles hard to apply and remember across the enterprise.

Architecture principles should guide IT deployment (A), apply broadly (B), reflect consensus (C), and relate to business objectives (E). They should NOT be subject to frequent amendment (D): principles are enduring guidelines. If they change often, they're not principles, they're tactical decisions.

A Technology Architecture document typically includes gap analysis reports, requirements traceability analysis, technology architecture models, and technical specifications for building blocks. Architecture contracts are separate legal/agreement documents created during implementation, not part of the architecture specification itself.

Interoperability is the ability of different systems or applications to work together and exchange information, even when they run on different platforms or are built by different vendors. This is a critical architectural characteristic for distributed systems and integration scenarios. Portability refers to running on different platforms, extensibility to adding features, scalability to handling growth, and serviceability to maintenance - none specifically address cross-platform communication.

Portability is the characteristic that describes how easily an application can be moved from one platform to another with minimal changes. This includes moving between different operating systems, hardware architectures, or cloud environments. Extensibility refers to adding new features, interoperability to cross-platform communication, availability to uptime, and serviceability to maintenance.

Serviceability is the ability to identify, diagnose, and fix problems in a running system without requiring downtime. This includes the ability to repair or upgrade components while the system continues to operate. Manageability is broader control, extensibility is adding features, availability is uptime, and usability is user-friendliness. Serviceability specifically focuses on maintenance and repair capabilities.

Nonfunctional criteria (or nonfunctional requirements) describe quality attributes and constraints rather than specific behaviors or features. Availability is a classic nonfunctional requirement - it specifies how available the system must be (e.g., 99.9% uptime). Requirements, defect density, failure modes, and specifications are either functional requirements or quality metrics, not nonfunctional criteria themselves.

Technology architecture models typically include technical views such as security, network/hardware, communications, and standards. The executive management view is a business/strategic perspective focused on governance and decision-making, not a technical architectural concern. While important for stakeholder communication, it doesn't contribute technical detail to the architecture model itself.

DAS (Direct Attached Storage) refers to storage devices directly connected to a server without a network in between. NAS (Network Attached Storage) is storage connected over a network. SAN (Storage Area Network) is a dedicated high-speed network for storage. SLS is not a standard storage term.

DAS is commonly deployed in small businesses because it's cost-effective and simpler to manage compared to SAN or NAS. Real-time applications typically use SAN for performance. High data volatility applications often require more scalable solutions. Larger enterprises typically use SAN or NAS for better scalability and centralized management.

Microsoft systems typically use CIFS (Common Internet File System) to connect to NAS for file sharing. NFS (Network File System) is typically used by Unix/Linux systems. BDMP and DART are not standard file sharing protocols.

NAS provides file-level access to clients, allowing them to access entire files over the network. Block-level access is provided by SAN. Direct disk access and logical block address access are characteristics of DAS, not NAS.

The Fibre Channel switch provides physical connections and logical routing between devices in a SAN fabric. Fibre cable is just the physical medium. HBA (Host Bus Adapter) connects servers to the fabric. Storage array contains the actual storage devices. The switch is the intelligent component that routes traffic.

The Name service in a fabric stores information about all devices attached, maintaining a database of device names and addresses. Login services handle device authentication. Fabric controller manages fabric-wide operations. Management server handles administrative functions.

Group mechanisms reduce the size of access control matrices by assigning permissions to groups rather than individuals - users inherit group permissions, dramatically reducing the matrix size. Function values and effective storage are not standard access control techniques. Suspended programs are unrelated to access control.

Grouping mechanisms reduce administrative overhead by allowing administrators to manage permissions for groups rather than individual users. Suspended programs are not relevant to administration. Reference monitors are security enforcement mechanisms. Resource manager handles resource allocation, not administrative efficiency.

The reference monitor is the security concept that mediates all accesses to objects by subjects, making access control decisions. It enforces security policies by checking each access request against authorization rules. Resource managers handle resource allocation, suspended programs are inactive processes, and access control matrix is a model for organizing permissions, not the decision mechanism itself.

The user who initiated the session is held accountable because they authenticated and established the session. Security accountability is tied to the authenticated identity, not the actual actor who may have hijacked the session. The network administrator manages the system, and the intruder is the attacker, not the accountable party. Resource managers handle storage allocation.

FC arbitrated loop (FC-AL) is the topology that uses hubs to connect devices in a loop, with arbitrated access to the loop. Switched fabric uses switches, not hubs. Mesh topologies (full or partial) require point-to-point connections between devices, not hub-based architecture. The hub is the defining characteristic of arbitrated loop topology.