Disaster recovery is a critical aspect of IT infrastructure management, ensuring that systems can be restored to normal operations after a catastrophic failure. In a Linux environment, disaster recovery involves a combination of backup strategies, redundancy, and failover mechanisms. This article will provide a comprehensive guide on how to implement disaster recovery in a Linux environment, emphasizing its importance and detailing practical steps to achieve it.

Examples:

1. Backup and Restore Using rsync

   • Backup Command:

     rsync -avz /source/directory/ /backup/directory/

     This command synchronizes the contents of /source/directory/ to /backup/directory/, preserving file permissions and timestamps.

   • Restore Command:

     rsync -avz /backup/directory/ /source/directory/

     This command restores the backup to the original directory.

2. Automated Backups with cron

   • Cron Job Setup:

     crontab -e

     Add the following line to schedule a daily backup at 2 AM:

     0 2 * * * rsync -avz /source/directory/ /backup/directory/

3. Database Backup Using mysqldump

   • Backup Command:

     mysqldump -u [username] -p[password] [database_name] > /backup/directory/database_backup.sql

   • Restore Command:

     mysql -u [username] -p[password] [database_name] < /backup/directory/database_backup.sql

4. Creating Disk Images with dd

   • Create Disk Image:

     dd if=/dev/sdX of=/backup/directory/disk_image.img

     Replace /dev/sdX with the appropriate disk identifier.

   • Restore Disk Image:

     dd if=/backup/directory/disk_image.img of=/dev/sdX

5. Implementing RAID for Redundancy

   • Install mdadm:

     sudo apt-get install mdadm

   • Create RAID 1 Array:

     sudo mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sdX /dev/sdY

   • Monitor RAID Array:

     cat /proc/mdstat

6. Setting Up a Failover Cluster with Pacemaker and Corosync

   • Install Packages:

     sudo apt-get install pacemaker corosync

   • Configure Corosync: Edit /etc/corosync/corosync.conf to define the cluster nodes and network settings.

   • Start Services:

     sudo systemctl start corosync
     sudo systemctl start pacemaker

   • Create Cluster Resources:

     sudo pcs cluster setup --name mycluster node1 node2
     sudo pcs cluster start --all
     sudo pcs resource create myresource ocf:heartbeat:IPaddr2 ip=192.168.1.100 cidr_netmask=24