Blob Storage Architecture

Comprehensive Azure Blob Storage design and file management architecture for the Grade My Investments platform.

BLOB STORAGE ARCHITECTURE

rendering diagram…

flowchart LR
    RE[Report Engine<br/>Linux VM]:::svc
    DL[Download Builder<br/>Linux VM]:::svc
    AF[Azure Functions<br/>API Layer]:::svc
    subgraph CONTAINERS[Azure Blob Storage Containers]
        C1[(reports<br/>Hot - 1 yr)]:::data
        C2[(gmi-downloads<br/>Hot - purge managed)]:::data
        C3[(user-uploads<br/>Hot - indefinite)]:::data
        C4[(system-backups<br/>Cool - 7 yr)]:::data
    end
    SAS{{SAS Token<br/>time-limited}}:::sec
    CLIENT[User Browser<br/>MAUI App]:::app

    RE -->|upload xlsx - json| C1
    DL -->|upload ZIP| C2
    CLIENT -->|upload file| AF
    AF -->|stream to| C3
    AF -->|generate| SAS
    SAS -->|direct download| CLIENT
    C1 -->|lifecycle policy| C4

    classDef app fill:#1f2630,stroke:#C0894E,color:#F3EFE8;
    classDef svc fill:#241c14,stroke:#E2B583,color:#F3EFE8;
    classDef data fill:#22201a,stroke:#C0894E,color:#EBD3AE;
    classDef ext fill:#1b1f27,stroke:#5A616B,color:#C4C0B8;
    classDef sec fill:#1d2733,stroke:#5cc8e0,color:#eafaff;

How reports flow from generation through blob containers to user download via SAS token.

Storage Overview

The Grade My Investments Blob Storage Architecture provides secure, scalable, and organized file storage for all generated reports, user uploads, and system assets. The architecture supports multiple storage tiers, automated lifecycle management, and seamless integration with the report generation pipeline.

Files are organized using a hierarchical container and folder structure that mirrors user account organization while maintaining security isolation and efficient access patterns.

Architecture Decisions

AI-Recommended Cost Optimization

During the Grade My Investments platform development, Claude AI recommended using Azure Blob Storage over database storage for report files - a decision that resulted in significant cost savings:

Original Design (Database Storage)

Store report files as BLOB data in Azure SQL Database
Simple implementation with direct SQL queries
Unified data access through Entity Framework
High storage costs per GB

Claude's Recommended Design (Blob Storage)

Store files in Azure Blob Storage containers
Store file metadata and URLs in database
Implement tiered storage for cost optimization
200x more cost-effective storage

Cost Impact Analysis

The architectural change from database to blob storage provided dramatic cost savings:

Azure SQL Database: ~$23 per GB/month for storage
Azure Blob Storage (Hot): ~$0.115 per GB/month
Cost Reduction: Approximately 200x less expensive for file storage
Annual Savings: Thousands of dollars for typical usage patterns

Storage Hierarchy

Container	Purpose	Access Tier	Retention
`reports`	Generated financial analysis reports	Hot	1 year
`user-uploads`	User-provided files and data	Hot	Indefinite
`system-backups`	Database and system backups	Cool	7 years
`temp-processing`	Temporary files during report generation	Hot	7 days
`archive`	Long-term storage for historical reports	Archive	10 years
`templates`	Report templates and system assets	Hot	Indefinite
`gmi-downloads`	ZIP downloads built by Download Builder service for folder exports	Hot	Managed by File Purge

Folder Structure

Reports Container

reports/

report-job-{id}/

job-{jobId}-{timestamp}.xlsx

summary-{jobId}.json

data-{jobId}.csv

File Naming Convention

Reports:
job-{jobId}-{timestamp}.xlsx

Backups:
db-backup-{date}-{time}.sql

Temp Files:
temp-{jobId}-{uuid}.tmp

Security & Access Control

Access Methods

SAS Tokens: Time-limited access for user downloads
Managed Identity: Service-to-service authentication
Connection Strings: Encrypted application-level access
RBAC: Role-based access control for administrators

Security Features

Encryption at Rest: Azure-managed AES-256 server-side encryption (SSE)
Encryption in Transit: HTTPS/TLS 1.2+
Private Endpoints: VNet-integrated access
Audit Logging: All access operations logged

Lifecycle Management

Hot Tier

Frequently accessed files

• Recent reports (30 days)
• User uploads
• System templates

Cool Tier

Infrequently accessed files

• Older reports (30-180 days)
• System backups
• Log files

Archive Tier

Long-term storage

• Historical reports (180+ days)
• Compliance data
• Disaster recovery

Performance Features

CDN integration
Parallel uploads
Chunked transfers
Compression optimization
Intelligent tiering

Storage Metrics

Total Capacity: 10 TB
Current Usage: 2.3 TB
File Count: ~50,000 files
Average File Size: 2.8 MB
Monthly Growth: 150 GB
Redundancy: LRS + GRS

Automated Processes

Lifecycle policies
Automated cleanup
Tier transitions
Backup verification
Cost optimization

Integration Points

Report Engine uploads
Web App downloads
Azure Functions processing
Mobile app access
Download Builder ZIP uploads
Backup services