Before managing Informix on Ubuntu, proper installation and configuration are critical. Start by creating a dedicated informix user and group (with UID/GID 3000 for consistency):
groupadd -g 3000 informix
useradd -u 3000 -g 3000 -d /home/informix -m informix
passwd informix
Set up environment variables in ~/.bash_profile (for the informix user) to define paths and server settings:
export INFORMIXDIR=/opt/IBM/informix
export INFORMIXSERVER=informix_server
export ONCONFIG=onconfig.informix
export LD_LIBRARY_PATH=$INFORMIXDIR/lib:$LD_LIBRARY_PATH
export PATH=$INFORMIXDIR/bin:$PATH
Install dependencies (e.g., build-essential, libpcre3-dev) via sudo apt-get install to avoid missing libraries during installation. Extract the Informix package to /opt/IBM/informix and run ./installserver to complete the installation. Configure critical files like onconfig.std (rename to onconfig.informix), /etc/services (add Informix service ports, e.g., informix_services 8888/tcp), and /opt/IBM/informix/etc/sqlhosts (define connection protocols—e.g., informix onsoctcp rouse informix_services). Initialize the database with onmode -ky (kill all connections) and oninit -iv (initialize).
Regular maintenance ensures optimal performance and prevents issues. Use onstat - commands to monitor key metrics:
onstat -g seg (check disk space usage by dbspaces),onstat -g sql (view active SQL sessions),onstat -g dyn (monitor dynamic memory usage).UPDATE STATISTICS), rebuild fragmented indexes (REBUILD INDEX), and clean up old logs. For example, automate index optimization with a cron job:0 3 * * * /opt/IBM/informix/bin/onstat -g idx | grep "Fragmentation > 30%" | awk '{print $1}' | xargs -I {} /opt/IBM/informix/bin/rebuild_index {}
Backup databases regularly using onbar (for tape backups) or ontape (for disk backups). Test restores periodically to validate backup integrity.
Performance tuning is a continuous process. Start with hardware: use SSDs for faster I/O, ensure sufficient RAM (allocate 1/4 of RAM to buffer pools), and use multi-core CPUs (configure numcpuvps in onconfig to match CPU cores). Optimize database configuration: adjust buffer pool sizes (BUFFERPOOL parameters), increase log buffer size (LOG_BUFFER), and enable connection pooling (NETTYPE for efficient network handling).
Indexing is crucial: create indexes on columns used in WHERE, JOIN, and ORDER BY clauses. Avoid over-indexing (each index adds write overhead). For example:
CREATE INDEX idx_customer_name ON customers(last_name, first_name);
Optimize queries by avoiding full table scans (use EXPLAIN to analyze query plans), minimizing subqueries (replace with JOINs where possible), and using covering indexes (indexes that include all queried columns). Partition large tables by range (e.g., by date) or hash to improve query performance and manageability.
Security is essential to protect data. Start with user access control: create roles with least-privilege permissions (e.g., READONLY role for reporting users) and avoid using the informix user for applications. Enforce strong password policies in onconfig:
PASSWORD_COMPLEXITY=3 (require uppercase, lowercase, numbers, and special characters),PASSWORD_MIN_LENGTH=8 (minimum password length),PASSWORD_EXPIRY_DAYS=90 (password expiration).Use encryption for data at rest (enable TDE—Transparent Data Encryption in onconfig) and in transit (use SSL/TLS for connections by configuring sqlhosts with onsoctcp or onipcssl). Regularly audit logs (e.g., onlog for login attempts) and monitor for suspicious activity (e.g., multiple failed login attempts).
Use built-in tools to monitor and troubleshoot Informix:
onstat - for general status, onstat -g ses for session details).oncheck -cDI to check indexes).onbar -b for incremental backups).For proactive monitoring, integrate with third-party tools like Zabbix or Prometheus to track CPU, memory, disk I/O, and database-specific metrics (e.g., buffer pool hit ratio, lock waits). Set up alerts for thresholds (e.g., disk space < 10%) to prevent downtime.
