Redundant database

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This guide covers methods for replicating, synchronizing, and migrating the VoIPmonitor CDR database between instances.

Overview

VoIPmonitor offers three methods for CDR synchronization:

Method Description Use Case
Database Backup Mode Dedicated sniffer reads from source DB, writes to destination DB Online migration, read-only replicas, hot-standby
Master-Master Replication Bidirectional MySQL/MariaDB replication Full HA with automatic failover (see Master-Master Replication)
Dual Write Sniffer writes CDRs to two databases simultaneously Real-time backup, centralized reporting

ℹ️ Note: All methods synchronize CDR data only. GUI settings (users, alerts, capture rules) must be migrated separately via Tools → Backup & Restore.

Database Backup Mode

A dedicated VoIPmonitor instance reads CDRs from a source database and writes them to a destination database. This is the recommended method for online GUI migration.

Architecture

Online GUI Migration Workflow

  1. Install VoIPmonitor GUI on the new server with a fresh database
  2. Backup configuration: On old GUI → Tools → Backup & Restore → backup configuration tables
  3. Restore configuration: On new GUI → upload the backup file (do this BEFORE starting migration)
  4. Create migration config file (see below)
  5. Start migration instance
  6. Once replication catches up, switch users to the new GUI
  7. Stop migration instance and decommission old server

Configuration

Copy the original config and modify for migration mode: 

scp root@old-server:/etc/voipmonitor.conf /etc/voipmonitor-migrate.conf

Required modifications in /etc/voipmonitor-migrate.conf: 

# 1. Avoid port conflict with production sniffer
managerport = 5030

# 2. DISABLE packet capture (comment out all interface lines)
# interface = eth0

# 3. Destination Database (NEW server - local)
mysqlhost      = 127.0.0.1
mysqldb        = voipmonitor
mysqlusername  = root
mysqlpassword  = new_password

# 4. Source Database (OLD server - remote)
database_backup_from_mysqlhost     = 192.168.0.1
database_backup_from_mysqldb       = voipmonitor
database_backup_from_mysqlusername = root
database_backup_from_mysqlpassword = old_password

# 5. Start date for replication
database_backup_from_date = 2024-01-01

# 6. Performance tuning
database_backup_insert_threads = 3   # Higher = faster but more load
database_backup_pause          = 3   # Higher = less load on source DB

Parameter Reference:

Parameter Description
database_backup_from_date Start date for sync (YYYY-MM-DD)
database_backup_insert_threads Parallel write threads (higher = faster, more load)
database_backup_pause Seconds between batches (higher = gentler on source DB)
database_backup_desc_dir Set yes to also write new incoming data to destination

Running the Migration

Test manually first: 

voipmonitor --config-file /etc/voipmonitor-migrate.conf -k -v 1

Run as systemd service:

Create /etc/systemd/system/voipmonitor-migrate.service: 

[Unit]
Description=VoIPmonitor Database Migration
After=network.target mysql.service

[Service]
Type=simple
ExecStart=/usr/local/sbin/voipmonitor -c /etc/voipmonitor-migrate.conf
Restart=on-failure

[Install]
WantedBy=multi-user.target

systemctl daemon-reload
systemctl enable --now voipmonitor-migrate

Dual Write Method

Configure the sniffer to write each CDR to both local and remote databases simultaneously.

Configuration

Add secondary database parameters to /etc/voipmonitor.conf: 

# Primary Database (local)
mysqlhost      = 127.0.0.1
mysqldb        = voipmonitor
mysqlusername  = root
mysqlpassword  = primary_password

# Secondary Database (remote) - enables dual write
mysql2host      = 192.168.1.100
mysql2db        = voipmonitor
mysql2username  = root
mysql2password  = secondary_password

⚠️ Warning: If the secondary database becomes unreachable, CDRs are written only to primary. Missed CDRs are NOT retroactively synced.

Comparison: Dual Write vs Master-Master

Aspect Dual Write Master-Master
Complexity Low (add mysql2* params) Medium (MySQL replication setup)
Bidirectional No Yes
GUI Settings Sync No Yes
Best For Simple one-way backup Full HA setup

Migrating PCAP Files

Database migration does NOT include PCAP files. Migrate separately using rsync: 

rsync -avz root@old-server:/var/spool/voipmonitor/ /var/spool/voipmonitor/

⚠️ Warning: Timezone must match between servers. PCAP paths use local timezone (spooldir/YYYY-MM-DD/HH/MM/). Mismatched timezones cause GUI to fail finding historical PCAPs. 

# Check timezone
timedatectl

# Set timezone
timedatectl set-timezone Europe/Prague

Schema Compatibility

The migration instance automatically handles database schema upgrades. This is useful when:

  • Migrating to different MySQL/MariaDB versions
  • Upgrading VoIPmonitor versions during migration
  • Moving from local MySQL to remote Percona

To identify schema changes manually: 

systemctl restart voipmonitor
tail -f /var/log/voipmonitor/voipmonitor.log | grep -E "CLI|ALTER|CREATE TABLE"

⚠️ Warning: For cross-version migration (e.g., MySQL 5.7 to 8.0), use the migration instance method instead of mysqldump. It handles schema differences automatically.

See Also

AI Summary for RAG

Summary: VoIPmonitor offers three CDR synchronization methods: (1) Database Backup Mode - a dedicated sensor reads from source DB and writes to destination DB for online migration or read-only replicas, configured with database_backup_from_* parameters; (2) Master-Master Replication - bidirectional MySQL replication for full HA (see separate article); (3) Dual Write - sniffer writes CDRs to both local and remote DB using mysql2* parameters. Key configuration: database_backup_from_date sets sync start date, database_backup_pause controls load on source DB (higher = less load), database_backup_insert_threads controls write parallelism. Migration instance must disable packet capture (comment out interface) and use different managerport. PCAP files must be migrated separately with rsync, ensuring timezone matches between servers. The migration instance automatically handles database schema upgrades when moving between MySQL/MariaDB versions.

Keywords: database replication, mysql backup, database migration, online migration, zero downtime, database_backup_from_date, database_backup_from_mysqlhost, database_backup_pause, database_backup_insert_threads, dual write, mysql2host, PCAP migration, rsync, timezone, schema upgrade, voipmonitor-migrate.conf, read-only replica, disaster recovery, high availability

Key Questions:

  • How can I migrate VoIPmonitor database with zero downtime?
  • What methods are available for database replication in VoIPmonitor?
  • What is the difference between database backup mode, dual write, and master-master replication?
  • How do I configure the migration instance (voipmonitor-migrate.conf)?
  • How can I control database load during replication (database_backup_pause)?
  • How do I configure dual write mode (mysql2* parameters)?
  • How do I migrate PCAP files to a new server?
  • Why is timezone matching important when migrating PCAP files?
  • Does the migration instance handle database schema upgrades automatically?
  • What configuration parameters are needed for database backup mode?
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