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YDB Capacity Calculator - Technical Specification

Overview

This document describes the technical implementation of the YDB Capacity Calculator, a single-page application that helps capacity planners determine server requirements for YDB clusters based on capacity needs or calculate capacity provided by a given server configuration.

Application Architecture

The application is a client-side single-page application built with:

  • HTML5 for structure
  • CSS3 for styling
  • Vanilla JavaScript for functionality
  • Local storage for data persistence

Core Components

1. HTML Structure

  • Header with application title and description
  • Mode toggle buttons for switching between use cases
  • Server configuration input section
  • Capacity requirements input section (Servers Needed mode)
  • Server count input (Resources Provided mode)
  • Calculate button
  • Results display section
  • Footer with YDB information

2. CSS Styling

  • Responsive design using CSS Grid and Flexbox
  • YDB color scheme implementation
  • Mobile-friendly layout
  • Clear visual hierarchy
  • Interactive elements with hover states

3. JavaScript Functionality

  • Form input validation
  • Calculation logic for both modes
  • Local storage integration
  • Dynamic UI updates
  • Error handling

Implementation Details

Servers Needed Mode

This functionality allows users to determine how many servers are needed based on capacity requirements.

Calculation Process

  1. Storage Groups Calculation

    • Each storage group consists of 9 VDisks
    • Reserve calculation (1% or minimum 18 VDisks)
    • VDisks per server calculation based on device count and VDisks per device
    • Server count calculation based on required VDisks

  2. CPU Cores Calculation

    • System reserve: 2-4 cores per server (using 2 as minimum)
    • Storage reserve: 6 cores per NVMe device, 0.5 per HDD device
    • Available cores for database nodes
    • Server count calculation based on required database cores

  3. RAM Calculation

    • System reserve: 4GB per server
    • Storage reserve: 6GB per NVMe device, 2GB per HDD device
    • Available RAM for database nodes
    • Server count calculation based on required database RAM

  4. Final Server Count

    • Takes the maximum of storage, CPU, and RAM requirements
    • Ensures minimum of 12 servers

Resources Provided Mode

This functionality allows users to determine what capacity is provided by a given server configuration and server count.

Calculation Process

  1. Storage Groups Calculation

    • Total VDisks calculation for HDD and NVMe
    • Reserve application (1% or minimum 18 VDisks)
    • Available VDisks after reserve
    • Storage groups calculation (9 VDisks per group)

  2. Database Cores Calculation

    • System reserve: 2 cores per server
    • Storage reserve: 6 cores per NVMe device, 0.5 per HDD device
    • Available cores per server for database nodes
    • Total database cores across all servers

  3. Database RAM Calculation

    • System reserve: 4GB per server
    • Storage reserve: 6GB per NVMe device, 2GB per HDD device
    • Available RAM per server for database nodes
    • Total database RAM across all servers

Data Persistence

  • Server configuration is saved to local storage on any change
  • Configuration is loaded from local storage on page load
  • Capacity requirements are not persisted (user may want different values each time)

Error Handling

  • Input validation for all numeric fields
  • Clear error messages for invalid inputs
  • Prevention of negative or zero server counts
  • Handling of edge cases (e.g., no devices specified)

Responsive Design

  • Adapts to different screen sizes
  • Mobile-friendly layout
  • Appropriate font sizes and spacing for all devices
  • Accessible color scheme

Business Rules Implementation

All business rules from the requirements document are implemented:

  • Storage group calculation with 9 VDisks per group
  • Reserve calculation (1% or minimum 18 VDisks)
  • System resource reservations (cores and RAM)
  • Storage device resource reservations
  • Calculation of available resources for database nodes
  • Minimum server count enforcement (12 servers)

File Structure

  • index.html: Main HTML file
  • css/styles.css: Styling
  • js/calculator.js: Calculation logic
  • docs/: Documentation files
    • requirements.md: Project requirements
    • user-stories.md: User stories
    • business-rules.md: Business rules
    • technical-specification.md: This document
    • resources-provided-technical-spec.md: Detailed specification for Resources Provided mode
    • ui-design.md: UI design documentation
    • user-guide.md: User instructions
    • project-summary.md: Project overview
    • test-results.md: Testing results

Testing

The application has been tested with various configurations to ensure:

  • Correct calculation of server requirements
  • Proper application of business rules
  • Accurate handling of edge cases
  • Responsive design on different devices
  • Data persistence functionality
  • Correct behavior when switching between modes