Data backup and disaster planning

Linux systems are widely used in servers and critical infrastructure, ensuring rapid recovery from failures is paramount. This page dives deep into the essentials of Linux system recovery, offering insights into effective backup strategies and disaster planning.

Types of Failures Affecting Linux Systems

• Hardware Failures: These include issues like hard drive crashes, memory corruption, or power supply failures.
• Software Issues: Software failures may involve bugs, accidental deletion of critical files, or system misconfigurations.
• Human Error: Often overlooked, human error such as incorrect commands or improper handling of data can lead to significant disruptions.
• Natural Disasters: Events like floods, earthquakes, or fires can cause physical damage to systems, necessitating robust disaster recovery plans.

Backup Strategies for Linux Systems

Incremental vs. Full Backups

• Incremental Backups save changes made since the last backup, conserving storage space and reducing backup time. However, recovery can be slower as it may require a series of incremental backups to restore the latest state.
• Full Backups involve copying all data to the backup storage. They require more storage space and longer to complete but make recovery fast and straightforward.

Local vs. Remote Backups

• Local Backups are stored on the same network or physical location as the primary system. They offer quick access and restoration capabilities. However, they are vulnerable to site-specific disasters like fires or power outages.
• Remote Backups are stored offsite and are crucial for recovering from natural disasters or major incidents affecting the primary site. They might introduce complexities in terms of data transfer speeds and access times.

Automated Backups

Linux offers several tools for automating backups, such as rsync for data synchronization and cron for scheduling automatic backup tasks. Automation ensures backups are performed consistently without human intervention, reducing the risk of missed backups due to oversight.

3-2-1 backup model

3 copies of data, 2 different backup mediums, 1 copy of data offsite. 3-2-1 model involves a multiphase bare metal restore and data recovery plan using following

• dd to make and restore production disk-images of configured servers for Block-by-Block Bare Metal Recovery Images
• rsync to make incremental backups of all user data
• Cpio, copy in/out, is a file archiver utility to create and extract archives or copy files to another place.
• tar & gzip and 7zip to store encrypted backups of files with passwords and notes from administrators. Commonly, this can be put on a USB drive, encrypted and locked in a safe that a Senior Manager access. Also, this ensures someone else will know vital security credentials if the current administrator wins the lottery and disappears to a sunny island somewhere. 7zip is installed and ready be used with 256-bit AES encryption for our tarball archives.

#7z encryption example - 7zip uses AES 256-bit encryption with an SHA-256 hash of the password and counter, repeated up to 512K times for key derivation. This should be secure enough if a complex key is used.
$7z a -p <output filename><input filename>
where, 
a: add to archive, and -p: encrypt and prompt for passphrase

Advanced Backup Techniques and Tools

Snapshot Technologies

Filesystem snapshots, such as those offered by LVM (Logical Volume Manager), Btrfs or ZFS, provide a way to capture the state of a filesystem at a particular point in time. These can be incredibly useful for creating quick backups without downtime.

Cloud-based Backup Solutions

Leveraging cloud storage for backups provides flexibility and scalability. However, it’s vital to consider data security and privacy issues, ensuring that data is encrypted both in transit and at rest.

Encryption and Security

Encrypting backup data is crucial to prevent unauthorized access. Use strong encryption standards and secure your backup locations physically and digitally.

Tools

• Relax-and-Recover (ReaR) is a GPL licensed setup-and-forget Linux bare metal disaster recovery solution. It is easy to set up and requires no maintenance so there is no excuse for not using it. Orcle provides good usage and guide on this page. With DRLM you can, easily and centrally, deploy and manage ReaR installations for all your GNU/Linux systems in your DataCenter(s).
• Bera Backup is a tool that makes back-up copies of folders and files of the server and of the server settings, everything necessary for restoring the original system exactly.