Resize & Migrate Instances

Scale your infrastructure vertically or move workloads across regions and providers with zero data loss and minimal downtime.

🕒 Updated: Mar 12, 2025 📄 v2.4.1 ⏱️ 8 min read

Vertical Resizing

Adjust CPU, RAM, and storage allocation for existing cloud instances. Resizing can be performed hot (live) for most configurations, or cold during a scheduled maintenance window.

ℹ️

Live resizing is supported for Standard and Performance tiers. Enterprise tiers require a 2-minute cold reboot for memory reallocation.

Prerequisites

Instance must be in a Running or Stopped state
Sufficient balance or approved credit limit on your account
Compatible image type (most Ubuntu, CentOS, and AlmaLinux images support live resize)

Step-by-Step Guide

Navigate to Instance Management

Open the CloudNexus Dashboard and select the target instance from your project view.

Configure New Specifications

Click Resize in the top toolbar. Select your desired vCPU, RAM, and disk tier. The system will validate compatibility and estimate costs.

Schedule or Apply Immediately

Choose Apply Now for live migration, or set a maintenance window for cold resizing. A confirmation modal will appear.

Verify & Validate

After completion, SSH into the instance and run lscpu and free -h to confirm new allocations.

⚠️

Downgrading storage below current used space is blocked to prevent data loss. You must delete or archive files before reducing disk size.

Cross-Region Migration

Move your instance between CloudNexus regions or import from external providers. Our migration wizard handles network reconfiguration, IP preservation options, and DNS updates automatically.

Migration Type	Downtime	Data Transfer	Cost
Intra-Region	< 30s	Internal backbone	Free
Cross-Region	2–5 min	Optimized TLS tunnel	$0.05/GB
External Import	Variable	AWS S3 / GCS / OCI	Standard egress rates

Migration Workflow

Initiate Migration Wizard

Go to Instances → Target Instance → Migrate. Select destination region and IP preference (Ephemeral or Static Reserved).

Network & DNS Mapping

The system generates a temporary migration IP. Update your DNS records to point to the new endpoint. TTL should be set to ≤300s before starting.

Execute & Monitor

Click Start Migration. Progress is tracked in real-time via the status panel and webhook callbacks.

Cutover & Rollback Plan

Once verification passes, finalize the migration. A snapshot is retained for 72 hours for instant rollback if anomalies occur.

✅

Tip: Use our cnx-migrate CLI tool to script bulk migrations with parallel streaming and automatic health checks.

CLI & API Reference

Automate scaling and migration workflows using the CloudNexus CLI or REST API v3.

Install CLI

bash

curl -fsSL https://cli.cloudnexus.io/install.sh | bash
cnx config set --token $CNX_API_KEY
cnx auth login

Resize Instance

bash

cnx instance resize --id inst-7a9b2x \\
  --cpus 8 \\
  --memory 32Gi \\
  --storage 400Gi \\
  --strategy live \\
  --confirm

REST API Endpoint

http

POST /v3/instances/{instance_id}/resize
Authorization: Bearer <token>
Content-Type: application/json

{
  "spec": {
    "vcpu": 8,
    "memory_gb": 32,
    "disk_gb": 400,
    "live_resize": true
  }
}

📖

Full schema documentation and rate limits are available in the API Reference section. Pagination uses cursor-based tokens for migrations >100 GB.

Frequently Asked Questions

Will my public IP change after resizing? ▼

No. Vertical resizing preserves your primary IP and reverse DNS records. Only cross-region migrations require IP changes unless you use Elastic IP reassignment. Static IPs remain bound to the instance UUID throughout the lifecycle.

What happens to my data during a cold resize? ▼

All block storage is mounted read-only during cold reallocation. CloudNexus takes an automatic snapshot before and after the operation. Zero data loss occurs under normal conditions. We recommend verifying checksums after reboot.

Can I migrate from AWS EC2 or DigitalOcean? ▼

Yes. Use the cnx migrate --source-provider aws --bucket s3://backup-vol command. We support raw disk images, EBS snapshots, and OpenStack Glance formats. Network rules and firewalls must be manually recreated as security groups are provider-specific.

How is billing calculated during migration? ▼

You are billed for the source instance until cutover completes. The destination instance begins billing at the exact second it becomes active. Data transfer fees apply only for cross-region and external migrations. Intra-region moves are free.