What are the common tools, strategies, and best practices for Linux system backup and recovery?

Linux system backup and recovery are important guarantees for data security, requiring mastery of various backup strategies and recovery methods.

Backup types:

• Full Backup: backup all data
• Incremental Backup: backup only data changed since last backup
• Differential Backup: backup data changed since last full backup
• Hot Backup: perform backup while system is running
• Cold Backup: perform backup while system is stopped

Backup tools:

• tar: archiving tool
  • Common options:
    • -c: create archive
    • -x: extract archive
    • -v: display detailed information
    • -f: specify archive file
    • -z: use gzip compression
    • -j: use bzip2 compression
  • Examples:
    • tar -czvf backup.tar.gz /path/to/backup: create compressed backup
    • tar -xzvf backup.tar.gz: extract compressed backup
    • tar -czvf backup-$(date +%Y%m%d).tar.gz /path/to/backup: backup with timestamp
• rsync: synchronization and backup tool
  • Common options:
    • -a: archive mode, preserve file attributes
    • -v: display detailed information
    • -z: compress during transfer
    • --delete: delete extra files in destination
    • --exclude: exclude files or directories
  • Examples:
    • rsync -avz /source/ /destination/: synchronize directories
    • rsync -avz --delete /source/ /destination/: synchronize and delete extra files
    • rsync -avz --exclude '*.log' /source/ /destination/: exclude log files
• dd: disk and partition backup tool
  • Examples:
    • dd if=/dev/sda of=/backup/sda.img: backup entire disk
    • dd if=/dev/sda1 of=/backup/sda1.img: backup partition
    • dd if=/backup/sda.img of=/dev/sda: restore disk
• dump/restore: filesystem backup tools (ext2/ext3/ext4)
  • dump -0u -f /backup/root.dump /: backup root filesystem
  • restore -rf /backup/root.dump: restore filesystem
• Bacula: enterprise-level backup solution
• Amanda: Advanced Maryland Automatic Network Disk Archiver
• Duplicity: encrypted backup tool
• Borg: deduplication backup tool

Database backup:

• MySQL:
  • mysqldump: logical backup tool
    • mysqldump -u root -p database > backup.sql: backup database
    • mysqldump -u root -p --all-databases > all.sql: backup all databases
    • mysqldump -u root -p --single-transaction database > backup.sql: consistent backup
    • mysql -u root -p database < backup.sql: restore database
  • mysqlhotcopy: physical backup tool (MyISAM)
  • Percona XtraBackup: physical backup tool (InnoDB)
• PostgreSQL:
  • pg_dump: logical backup tool
    • pg_dump database > backup.sql: backup database
    • pg_dumpall > all.sql: backup all databases
    • psql database < backup.sql: restore database
  • pg_basebackup: physical backup tool
• MongoDB:
  • mongodump: backup tool
  • mongorestore: recovery tool

System backup strategy:

• 3-2-1 principle:
  • 3 backup copies
  • 2 different media
  • 1 offsite backup
• Backup frequency:
  • Full backup: once a week
  • Incremental backup: once a day
  • Differential backup: once a day
• Retention policy:
  • Daily backups kept for 7 days
  • Weekly backups kept for 4 weeks
  • Monthly backups kept for 12 months
• Automated backup:
  • Use cron to execute backup scripts regularly
  • Example:

    bash
    #!/bin/bash
    BACKUP_DIR="/backup"
    DATE=$(date +%Y%m%d)
    tar -czvf $BACKUP_DIR/backup-$DATE.tar.gz /path/to/backup
    find $BACKUP_DIR -name "backup-*.tar.gz" -mtime +7 -delete

Cloud backup solutions:

• AWS S3: object storage service
• Azure Blob Storage: Azure object storage
• Google Cloud Storage: Google cloud storage
• Alibaba Cloud OSS: Alibaba cloud object storage
• Tencent Cloud COS: Tencent cloud object storage
• rclone: multi-cloud storage synchronization tool

Backup verification:

• Regularly test recovery process
• Verify backup integrity
• Check backup file size
• Use checksums to verify data

Recovery strategies:

• Full recovery: recover from full backup
• Incremental recovery: start from full backup, apply incremental backups in sequence
• Differential recovery: start from full backup, apply latest differential backup
• Point-in-time recovery: recover to specified point in time (requires binlog)
• Disaster recovery: offsite backup recovery

Backup best practices:

• Document backup strategy
• Automate backup process
• Regularly test recovery
• Encrypt sensitive data
• Monitor backup status
• Keep multiple backup versions
• Offsite backup
• Regularly review backup strategy
• Document recovery process

Troubleshooting:

• Backup failure: check disk space, permissions, network connection
• Recovery failure: verify backup file integrity, check destination path
• Performance issues: optimize backup time, use incremental backups
• Insufficient storage: clean old backups, use compression