# Verify disks
lsblk
# sda: 12TB (IronWolf #1)
# sdb: 12TB (IronWolf #2)

# Create RAID 1 (mirror)
sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sda /dev/sdb

# Create filesystem
sudo mkfs.ext4 /dev/md0

# Mount
sudo mkdir -p /backup
sudo mount /dev/md0 /backup

# Persist in /etc/fstab
echo '/dev/md0 /backup ext4 defaults 0 2' | sudo tee -a /etc/fstab

# Save RAID config
sudo mdadm --detail --scan | sudo tee -a /etc/mdadm/mdadm.conf

# Install NFS server
sudo apt install nfs-kernel-server

# Create share directories
sudo mkdir -p /backup/server-{a,b,c}

# Configure /etc/exports
# Allow access only from server subnet
echo '/backup/server-a 10.x.10.0/24(rw,sync,no_subtree_check,root_squash)' | sudo tee -a /etc/exports

# Apply and start
sudo exportfs -ra
sudo systemctl enable --now nfs-kernel-server

# Verify shares
showmount -e localhost

# On each production server (client)
sudo apt install nfs-common

sudo mkdir -p /mnt/backup
sudo mount -t nfs 10.x.10.20:/backup/server-a /mnt/backup

# Verify
df -h /mnt/backup

# Persist in /etc/fstab
echo '10.x.10.20:/backup/server-a /mnt/backup nfs defaults,_netdev,soft,timeo=150 0 0' \
  | sudo tee -a /etc/fstab

# _netdev: mount after network is ready
# soft: timeout on NFS server down (hard = wait forever)
# timeo=150: 15-second timeout

#!/bin/bash
# /usr/local/bin/backup.sh

BACKUP_DIR="/mnt/backup"
LOG_FILE="/var/log/backup.log"
DATE=$(date '+%Y-%m-%d %H:%M:%S')

# Verify NFS mount
if ! mountpoint -q $BACKUP_DIR; then
    echo "[$DATE] ERROR: NFS not mounted" >> $LOG_FILE
    exit 1
fi

# Backup critical directories
rsync -avz --delete \
    --exclude='.cache' \
    --exclude='node_modules' \
    --exclude='__pycache__' \
    /home/ $BACKUP_DIR/home/ >> $LOG_FILE 2>&1

rsync -avz --delete /etc/ $BACKUP_DIR/etc/ >> $LOG_FILE 2>&1
rsync -avz --delete /var/lib/docker/volumes/ $BACKUP_DIR/docker-volumes/ >> $LOG_FILE 2>&1

# Database dump + backup
pg_dumpall -U postgres > /tmp/db_backup.sql 2>/dev/null
if [ -f /tmp/db_backup.sql ]; then
    rsync -avz /tmp/db_backup.sql $BACKUP_DIR/db/ >> $LOG_FILE 2>&1
    rm /tmp/db_backup.sql
fi

echo "[$DATE] Backup completed" >> $LOG_FILE

sudo chmod +x /usr/local/bin/backup.sh

# Add to crontab (daily at 2 AM)
sudo crontab -e
# Add: 0 2 * * * /usr/local/bin/backup.sh

# Backup server netplan (/etc/netplan/01-config.yaml)
network:
  ethernets:
    eth0:
      addresses: [10.x.10.20/24]
      routes:
        - to: default
          via: 10.x.10.1
    eth1:
      addresses: [10.x.50.20/24]
      # No default gateway on backup NIC

# Mount NFS via backup-dedicated IP
sudo mount -t nfs 10.x.50.20:/backup/server-a /mnt/backup

sudo apt install smartmontools
sudo smartctl -a /dev/sda

# Key attributes:
# Reallocated_Sector_Ct: reallocated sectors (must be 0)
# Current_Pending_Sector: pending bad sectors (must be 0)
# Temperature_Celsius: drive temp (under 40°C recommended)

# RAID status
cat /proc/mdstat
# md0 : active raid1 sda[0] sdb[1]
# [UU] ← both healthy

#!/bin/bash
# /usr/local/bin/backup-check.sh

LOG="/var/log/backup.log"
TODAY=$(date '+%Y-%m-%d')

# Check today's backup completion
if grep -q "$TODAY.*Backup completed" $LOG; then
    echo "OK: Backup completed"
else
    echo "WARNING: Today's backup not completed!"
fi

# Disk usage check
USAGE=$(df -h /backup | tail -1 | awk '{print $5}' | tr -d '%')
if [ "$USAGE" -gt 85 ]; then
    echo "WARNING: Backup disk at $USAGE%"
fi

# RAID status check
if ! grep -q "\[UU\]" /proc/mdstat; then
    echo "CRITICAL: RAID disk failure detected!"
fi