Enterprise Application and Database Hosting Architecture

This module defines the application and database hosting layers of the Enterprise Hybrid HCI Platform. It provides a reusable pattern for deploying internal business applications, web services, API platforms, and relational database systems across the Primary DC, Disaster Recovery DC, and Out of Region DR site.

These tiers are tightly integrated with the platform services, fabric, and DMZ layers described in earlier modules. They follow the same principles of identity awareness, microsegmentation, and continuous verification that govern the entire architecture.

Application Hosting Model

The architecture uses a structured application tiering model that separates web, application, and data functions. This ensures predictable performance, controlled access paths, and strong security boundaries.

The three application tiers are:

• Web Tier
• Application Tier
• Database Tier

Each tier resides on its own HCI block or segment and maps directly to the enterprise segmentation model.

Web Tier

The Web Tier hosts internal web servers, service portals, and applications accessed through the DMZ or internal networks.

Responsibilities

• Serve internal and authenticated web interfaces
• Act as presentation and user interaction layer
• Enforce authentication and authorization via identity provider integration
• Terminate TLS connections from internal networks or re encrypted DMZ traffic
• Forward requests to the Application Tier via strictly defined paths

Deployment Pattern

Web Tier workloads run on:

• Dedicated segments within the Application Hosting HCI Block
• Virtual servers or application platforms capable of auto scaling
• Reverse proxies or internal load balancers used for distribution and health checking

Security considerations:

• Only the DMZ reverse proxy may reach published web servers
• Web servers may not reach the internet directly
• Administrative access flows from management networks only
• Logging is forwarded to centralized SIEM

Integration with MFA and identity providers ensures consistent session security.

Application Tier

The Application Tier hosts backend application logic, business services, and APIs that support internal and external operations.

Responsibilities

• Execute business logic
• Process authenticated requests from the Web Tier
• Communicate with the Database Tier for data retrieval
• Expose internal only services to other enterprise applications
• Implement role and policy based access controls

Deployment Pattern

Application Tier workloads run on:

• Dedicated VLANs or segments in the Application Hosting HCI Block
• Virtual machines or containerized platforms
• Internal load balancers for API distribution
• Identity aware routing policies that control which web servers may call which APIs

Security considerations:

• No direct user access is permitted to the Application Tier
• Only the Web Tier and other trusted backend systems may reach it
• Application to application communication paths are explicitly defined
• Credentials and secrets are stored in secure vaults, not in application code

Microsegmentation reduces blast radius and prevents lateral movement across applications.

Containerized Workloads and Kubernetes Integration

Many organizations deploy microservices or API driven applications on Kubernetes.

Responsibilities

• Host stateless microservices, APIs, batch jobs, and internal services
• Integrate with platform services such as identity providers and monitoring
• Provide horizontal scaling for performance and resiliency

Deployment Pattern

Kubernetes clusters run in the Kubernetes HCI Block as defined in earlier modules.

Key architecture elements:

• Ingress controllers that enforce internal reverse proxy standards
• Network policies that limit pod to pod communication
• Service meshes when needed for identity based service to service authentication
• CSI backed persistent storage for stateful workloads
• Integration with internal CI/CD pipelines

Kubernetes follows the same segmentation rules as virtualized application workloads. Internal applications do not become reachable from DMZ or user networks unless explicitly published through DMZ gateways.

Database Hosting Model

The Database Tier manages structured and semi structured data using relational database systems, high performance storage, and replication engines.

It is isolated at both the network and identity levels to ensure integrity and confidentiality.

Database Tier

The Database Tier hosts:

• Relational database engines
• Application specific data stores
• High performance OLTP platforms
• Messaging systems and data pipeline components when aligned to the architecture

Responsibilities

• Process queries and transactions from the Application Tier
• Provide consistent and durable storage
• Support defined RPO and RTO targets via replication
• Enforce strict authentication and least privilege permissions
• Maintain separation between application schemas and administrative functions

Deployment Pattern

Database workloads run on:

• The Database and High Performance Storage HCI Block
• Virtual machines with optimized CPU, RAM, and storage resources
• Cloud integrated replication tools when hybrid patterns are used

Security considerations:

• Only approved Application Tier or platform services may reach database services
• Database administrators access systems through VDI based, identity controlled workflows
• Secrets and connection strings are stored in vaults and rotated regularly
• Database audit logs are forwarded to SIEM for continuous verification

Databases never exist in or communicate directly with the DMZ.

Storage Layout and Performance Tiers

Storage is a critical part of the Database Tier.

Typical patterns include:

• NVMe backed storage for high performance transactional workloads
• SSD backed storage for general purpose workloads
• Replication enabled storage policies for production databases
• Snapshot based recovery mechanisms for development or staging data

Performance tiers align with application criticality and data classification. Tier 1 systems receive synchronous replication and strict backup schedules.

Database High Availability Patterns

The architecture supports multiple high availability approaches depending on technology and requirements.

Common Models

• Active passive clustering via OS or database native clustering
• Active active replication for read scaling
• Log shipping or asynchronous replication for non critical systems
• Cloud based replicas for hybrid data protection

These models are implemented across both the Primary DC and DR DC.

Out of Region DR relies on asynchronous replication and recovery workflows tested during DR exercises.

Application to Database Access Controls

Zero trust principles apply at every boundary between Application and Database Tiers.

Access controls include:

• Network segmentation that blocks all unauthorized east and west traffic
• Identity based authentication for database users and service accounts
• Role based access for application schemas
• Privileged access workflows for DBAs
• Monitoring of all query level activity in sensitive systems

All database access events are logged and forwarded to SIEM. Behavioral analysis tools may flag anomalous query patterns.

Logging, Monitoring, and Telemetry

Observability ensures application and database tiers operate securely and efficiently.

Application Tier Telemetry

• Application logs forwarded to SIEM
• API gateway and reverse proxy logs included
• Performance metrics collected through monitoring platforms
• Synthetic transaction checks for user experience monitoring

Database Tier Telemetry

• Query logs, slow query logs, and error logs
• Storage latency, IOPS, and throughput
• Replication health and failover readiness
• Alerts integrated with operations and incident response workflows

Telemetry flows through allow list based paths from HCI blocks to the Infrastructure HCI Block collectors.

Zero Trust Alignment

Application and Database Tiers follow the three pillars of the zero trust model defined in earlier modules.

Identity Aware Flows

• Applications authenticate with internal identity providers
• Database logins are tied to service accounts or user identities
• API access depends on authorization policies, not network reachability
• Administrative actions require MFA and privileged access workflows

Microsegmentation

• Each application tier is placed in its own segment
• Applications communicate only with explicitly allowed targets
• Database servers remain isolated from user networks, DMZ, and unrelated applications
• Host level firewalls provide an additional boundary

Continuous Verification

• Application and database telemetry feed SIEM for real time monitoring
• Anomalous behavior leads to automated alerts or enforcement actions
• Vulnerability scanning feeds into risk scoring and patch prioritization
• Kubernetes and virtualized workloads receive continuous security posture assessments

Implementation Options

The following products represent common vendor ecosystems that can implement the described architecture.

Application Hosting Platforms

• Virtualized workloads on VMware vSphere or Nutanix AHV
• Containerized workloads on Kubernetes platforms such as Red Hat OpenShift, VMware Tanzu, or Rancher

Web and API Hosting

• Internal reverse proxies using NGINX or HAProxy
• API gateways such as Kong or Apigee
• Internal load balancers integrated with DMZ publishing layers

Databases

• Microsoft SQL Server
• PostgreSQL
• Oracle Database
• MySQL and MariaDB
• Distributed SQL engines for specialized use cases

Storage

• VMware vSAN
• Nutanix storage
• Dell PowerStore or PowerFlex
• HPE Alletra or Nimble

Monitoring and Telemetry

• Prometheus and Grafana
• Application performance monitoring tools
• SIEM platforms such as Splunk, Elastic Stack, or Microsoft Sentinel

This application and database hosting architecture provides a secure and scalable model for delivering enterprise applications. It aligns with zero trust requirements, supports multi site resiliency, and integrates with the platform services described in earlier modules.