Tips for Migrating a Multisite Without Downtime

Introduction

Migrating a WordPress Multisite network can be daunting—especially when zero downtime is required. Whether you’re moving between hosts, data centers, or upgrading infrastructure, meticulous planning and execution are critical. This guide presents
comprehensive, practical tips to migrate your multisite network smoothly, maintain business continuity, and preserve SEO equity.

1. Understanding Your Multisite Setup

• Topology: Subdomains (site1.example.com) vs. subdirectories (example.com/site1), or custom domains.
• Plugins Themes: Identify network-activated vs. site-specific resources.
• Traffic Patterns: Peak hours, geographic distribution, API endpoints.
• Storage Needs: Filesystem volume sizes, upload directories, backups.

2. Pre-Migration Planning

2.1 Infrastructure Assessment

• Benchmark performance on source server: CPU, RAM, I/O.
• Estimate target resources—use cloud autoscaling if needed.
• Review PHP versions, MySQL/MariaDB compatibility.

2.2 DNS and Networking Strategy

• Use low-TTL records (300s) to accelerate DNS switchover. See Cloudflare DNS Guide.
• Consider CNAME flattening or ALIAS records for apex domains.
• Plan for IPv6/IPv4 support (dual-stack).

3. Setting Up a Staging Environment

Mirror your live network in a staging environment:

1. Clone database and wp-content directory using WP-CLI for consistency.
2. Use containerization (Docker) or virtualization for parity: replicating OS, PHP, Nginx/Apache versions.
3. Install necessary caching layers (Redis, Memcached) and test plugin compatibility.

4. Database and File Synchronization

4.1 Incremental Sync with rsync and binlogs

• Initial full rsync of wp-content/uploads with rsync -aH --delete.
• Enable MySQL binary logging apply incremental changes up to the “freeze” point.
• Scripted cron jobs for periodic syncs during cutover window.

4.2 Handling Large Tables

• Use mysqldump --single-transaction for InnoDB tables to avoid locking.
• Split dumps by table size—e.g., wp_posts, wp_postmeta.

5. DNS and Network Configuration

Plan your DNS cutover meticulously:

Action	Timeframe	Notes
Lower TTL to 300s	T – 48h	Reduces propagation delay
Deploy new DNS records	T – 1h	Point to new IPs/load balancers
Final sync cutover	T	Freeze uploads till migration completes

6. SSL/TLS Certificates

• Obtain wildcard or SAN certificates for all sites. See Let’s Encrypt.
• Deploy certificates on new servers—test via openssl s_client.
• Ensure HSTS and OCSP stapling are configured properly.

7. Testing and Validation

1. Functional tests: site load, login, form submissions, APIs.
2. Performance tests: use load testing tools like Loader.io or ApacheBench.
3. SEO verification: Ensure 200 HTTP status, no 404s. Use Screaming Frog or similar crawlers.
4. Security audit: run WPScan or similar to validate plugin/theme vulnerabilities.

8. Go-Live Strategy

• Maintenance Mode: Briefly enable network-wide maintenance to prevent content drift.
• Rolling DNS Cutover: Gradually shift traffic from old to new IPs using weighted DNS or traffic director.
• Health Checks: Monitor response codes, error logs, and resource usage.

9. Rollback and Fallback Planning

• Preserve original DNS TTLs in case you need to revert quickly.
• Keep backups of database/binlogs and file snapshots until post-migration stability is confirmed.
• Document rollback steps: database restore, file sync reversal, DNS re-pointing.

10. Post-Migration Monitoring Optimization

• Implement real-time monitoring with tools like New Relic, Datadog, or Prometheus.
• Analyze logs (ELK stack) for 5xx errors, slow queries.
• Gradually re-enable caching layers (Varnish, CDN) and test invalidation rules.
• Solicit user feedback for any UI inconsistencies or broken links post-migration.

Conclusion

Successful multisite migrations demand a blend of technical rigor, rehearsed procedures, and clear communication among stakeholders. By following these tips—comprehensive planning, incremental synchronization, strategic DNS management, meticulous testing, and robust rollback plans—you can achieve a seamless migration with zero downtime.

Further Reading: WordPress Multisite Introduction Multisite Network Administration