Database Backup Strategies - automated dumps, point-in-time recovery

📆 · ⏳ 6 min read ·
# devops # postgres
¡

If you don’t have backups, you don’t have data. Period.

Your production database just corrupted. Last backup was 3 days ago. You’re about to explain to customers why their data is gone forever while you scramble through corrupted log files hoping to recover something.

Reality check: Your database will fail. Hardware dies, humans make mistakes, software has bugs, and ransomware exists. The question isn’t if you’ll need backups - it’s whether you’ll have them when disaster strikes at 3 AM on a Sunday.

The Reality of Database Disasters

Common failure scenarios:

  • Disk corruption (hardware failure)
  • Accidental DROP TABLE or DELETE without WHERE
  • Application bug corrupting data
  • Ransomware targeting databases
  • Failed migration destroying production data

Recovery time objectives:

  • Hobby project: 1-2 days acceptable
  • Side business: 4-6 hours maximum
  • Production app: 15-30 minutes target

Backup Strategy Breakdown

Level 1: Basic Automated Dumps

Good for: Small databases (< 10GB), daily recovery acceptable

backup_postgres.sh
#!/bin/bash


DB_NAME="myapp"
DB_USER="myapp"
BACKUP_DIR="/var/backups/postgres"
DATE=$(date +%Y%m%d_%H%M%S)
RETENTION_DAYS=30


mkdir -p $BACKUP_DIR


# PostgreSQL backup
docker compose exec -T postgres pg_dump -U $DB_USER -Fc $DB_NAME > "$BACKUP_DIR/${DB_NAME}_$DATE.dump"


# Cleanup old backups
find $BACKUP_DIR -name "${DB_NAME}_*.dump" -mtime +$RETENTION_DAYS -delete


echo "Backup completed: ${DB_NAME}_$DATE.dump"

Schedule it:

Terminal window
# Run daily at 2 AM
echo "0 2 * * * /usr/local/bin/backup_postgres.sh >> /var/log/backup.log 2>&1" | sudo crontab -

Level 2: WAL Archiving (Point-in-Time Recovery)

Good for: Critical databases, need recovery to specific timestamp

PostgreSQL WAL setup in postgresql.conf:

Terminal window
# WAL settings for PITR
wal_level = replica
archive_mode = on
archive_command = 'cp %p /var/backups/postgres/wal/%f'
max_wal_size = 2GB
checkpoint_completion_target = 0.9
wal_keep_size = 1GB

Create WAL archive directory:

Terminal window
sudo mkdir -p /var/backups/postgres/wal
sudo chown postgres:postgres /var/backups/postgres/wal
sudo chmod 700 /var/backups/postgres/wal

Base backup script:

base_backup.sh
#!/bin/bash


BACKUP_DIR="/var/backups/postgres/base"
DATE=$(date +%Y%m%d_%H%M%S)


mkdir -p $BACKUP_DIR


# Create base backup
docker compose exec -T postgres pg_basebackup -U postgres -D /tmp/backup -Ft -z -P
docker compose exec -T postgres tar -czf /tmp/base_backup_$DATE.tar.gz /tmp/backup
docker cp $(docker compose ps -q postgres):/tmp/base_backup_$DATE.tar.gz $BACKUP_DIR/


echo "Base backup completed: base_backup_$DATE.tar.gz"

PITR Recovery process:

Terminal window
# Stop PostgreSQL
docker compose stop postgres


# Restore base backup
cd /var/backups/postgres/base
tar -xzf base_backup_20241030_020000.tar.gz


# Create recovery.conf
cat > recovery.conf << EOF
restore_command = 'cp /var/backups/postgres/wal/%f %p'
recovery_target_time = '2024-10-30 14:30:00'
recovery_target_action = 'promote'
EOF


# Start PostgreSQL - it will recover to the specified time
docker compose start postgres

Level 3: Continuous Backup with pgBackRest

Good for: Production databases, automated PITR, multiple retention policies

Install pgBackRest:

Terminal window
sudo apt install pgbackrest -y

Configure /etc/pgbackrest.conf:

Terminal window
[global]
repo1-path=/var/lib/pgbackrest
repo1-retention-full=3
repo1-retention-diff=3
process-max=4


[myapp]
pg1-path=/var/lib/postgresql/data
pg1-port=5432
pg1-user=postgres

PostgreSQL configuration:

Terminal window
# Add to postgresql.conf
archive_command = 'pgbackrest --stanza=myapp archive-push %p'

Setup and run:

Terminal window
# Create stanza
sudo -u postgres pgbackrest --stanza=myapp stanza-create


# Full backup (run weekly)
sudo -u postgres pgbackrest --stanza=myapp backup --type=full


# Incremental backup (run daily)
sudo -u postgres pgbackrest --stanza=myapp backup --type=diff


# Point-in-time recovery
sudo -u postgres pgbackrest --stanza=myapp restore --type=time --target="2024-10-30 14:30:00"

Cloud Storage Integration

S3-Compatible Storage

Setup rclone for cloud backups:

Terminal window
# Install rclone
sudo apt install rclone -y


# Configure (interactive setup)
rclone config


# Test connection
rclone ls mycloud:mybucket

Enhanced backup script with cloud sync:

#!/bin/bash


LOCAL_BACKUP_DIR="/var/backups/postgres"
CLOUD_REMOTE="mycloud:postgres-backups"
DATE=$(date +%Y%m%d_%H%M%S)


# Create local backup
docker compose exec -T postgres pg_dump -U myapp -Fc myapp > "$LOCAL_BACKUP_DIR/myapp_$DATE.dump"


# Sync to cloud storage
rclone copy $LOCAL_BACKUP_DIR $CLOUD_REMOTE --include "*.dump" --transfers=4


# Cleanup local files older than 7 days
find $LOCAL_BACKUP_DIR -name "*.dump" -mtime +7 -delete


# Cleanup cloud files older than 90 days
rclone delete $CLOUD_REMOTE --min-age 90d


echo "Backup synced to cloud: myapp_$DATE.dump"

Hetzner Storage Box Integration

Mount Storage Box:

Terminal window
# Install dependencies
sudo apt install cifs-utils -y


# Create credentials file
sudo mkdir -p /etc/cifs
echo "username=your-username" | sudo tee /etc/cifs/hetzner-credentials
echo "password=your-password" | sudo tee -a /etc/cifs/hetzner-credentials
sudo chmod 600 /etc/cifs/hetzner-credentials


# Mount storage box
sudo mkdir /mnt/backup
echo "//your-username.your-server.de/backup /mnt/backup cifs credentials=/etc/cifs/hetzner-credentials,uid=1000,gid=1000,iocharset=utf8 0 0" | sudo tee -a /etc/fstab
sudo mount -a

Direct backup to Storage Box:

#!/bin/bash
# Direct backup to Hetzner Storage Box


BACKUP_DIR="/mnt/backup/postgres"
DATE=$(date +%Y%m%d_%H%M%S)


mkdir -p $BACKUP_DIR


# Backup directly to storage box
docker compose exec -T postgres pg_dump -U myapp -Fc myapp > "$BACKUP_DIR/myapp_$DATE.dump"


# Keep 90 days on storage box
find $BACKUP_DIR -name "*.dump" -mtime +90 -delete


echo "Backup completed to Storage Box: myapp_$DATE.dump"
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Monitoring and Alerting

Backup Health Check

/usr/local/bin/check_backup_health.sh
#!/bin/bash
BACKUP_DIR="/var/backups/postgres"
ALERT_EMAIL="[email protected]"
MAX_AGE_HOURS=26  # Alert if backup older than 26 hours


# Find latest backup
LATEST_BACKUP=$(find $BACKUP_DIR -name "*.dump" -type f -printf '%T@ %p\n' | sort -n | tail -1 | cut -d' ' -f2-)
BACKUP_AGE_HOURS=$((($(date +%s) - $(stat -c %Y "$LATEST_BACKUP")) / 3600))


if [ $BACKUP_AGE_HOURS -gt $MAX_AGE_HOURS ]; then
    echo "ALERT: Latest backup is $BACKUP_AGE_HOURS hours old" | mail -s "Backup Alert" $ALERT_EMAIL
    exit 1
fi


# Test backup integrity
if docker compose exec -T postgres pg_restore --list "$LATEST_BACKUP" > /dev/null 2>&1; then
    echo "Backup integrity check passed"
else
    echo "ALERT: Backup integrity check failed" | mail -s "Backup Corruption Alert" $ALERT_EMAIL
    exit 1
fi

Schedule health checks:

Terminal window
# Run every 4 hours
echo "0 */4 * * * /usr/local/bin/check_backup_health.sh" | crontab -

Recovery Testing

Automated Recovery Testing

/usr/local/bin/test_recovery.sh
#!/bin/bash
TEST_DB="myapp_recovery_test"
BACKUP_FILE="/var/backups/postgres/myapp_20241030_020000.dump"


# Create test database
docker compose exec -T postgres createdb -U postgres $TEST_DB


# Restore backup to test database
docker compose exec -T postgres pg_restore -U postgres -d $TEST_DB "$BACKUP_FILE"


# Run basic integrity checks
RECORD_COUNT=$(docker compose exec -T postgres psql -U postgres -d $TEST_DB -t -c "SELECT COUNT(*) FROM users;")
if [ "$RECORD_COUNT" -gt 0 ]; then
    echo "Recovery test passed: $RECORD_COUNT records restored"
else
    echo "Recovery test failed: No records found"
fi


# Cleanup test database
docker compose exec -T postgres dropdb -U postgres $TEST_DB

What Could Go Wrong

Common Backup Failures

Backup script permissions:

Terminal window
# Fix permissions
sudo chown postgres:postgres /var/backups/postgres
sudo chmod 755 /var/backups/postgres

Insufficient disk space:

Terminal window
# Monitor backup directory size
df -h /var/backups
du -sh /var/backups/postgres/*


# Compress old backups
find /var/backups -name "*.dump" -mtime +7 -exec gzip {} \;

Network timeouts to cloud storage:

Terminal window
# Add retry logic to rclone
rclone copy $LOCAL_BACKUP_DIR $CLOUD_REMOTE --retries 3 --low-level-retries 10

Recovery Troubleshooting

Corrupted backup file:

Terminal window
# Test backup integrity before recovery
pg_restore --list backup.dump | head -10

Missing WAL files:

Terminal window
# Check WAL archive directory
ls -la /var/backups/postgres/wal/


# Verify archive_command is working
docker compose exec postgres psql -c "SELECT pg_switch_wal();"

Reality Check

Setup time: 2-4 hours for comprehensive backup strategy

Storage costs (monthly):

  • Local: 50GB = included in VPS storage (CAX11 has 40GB, CAX21 has 80GB)
  • Hetzner ↗️ Storage Box: 100GB = $3.20/month
  • AWS S3: 100GB = $2.30/month + transfer costs

Critical decision: Point-in-time recovery adds complexity but saves hours during actual disasters. Worth it for any database you can’t afford to lose.

Most production issues come from:

  1. No backup testing - backups exist but are corrupted
  2. Missing WAL files - gaps in point-in-time recovery chain
  3. Slow recovery - no documented recovery procedures

Test your recovery process monthly. When disaster strikes, you want muscle memory, not learning.

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