Backup Strategy Design and Validation
📌 The session objective is to design and validate a backup strategy based on policies, application configuration, and backup scheduling, including performing a test restore.
🚨 A critical failure scenario involves a server crash where the last backup location and restoration status are unknown, emphasizing the need for proactive system administration.
⚙️ System administrators must follow a structured maintenance process to ensure data safety, stable updates, and early issue detection, moving from a reactive to a proactive stance.
💾 Performing backups is an essential, though often ignored or sloppily done, duty for system administrators, requiring verification of data integrity and correct execution.

Backup Policy Definition (RPO, RTO, Retention, Security)
📈 RPO (Recovery Point Objective) defines the maximum acceptable data loss, directly tied to the frequency of transactions (e.g., RPO must be less than 0.5 seconds if transactions occur every 0.5 seconds).
⏱️ RTO (Recovery Time Objective) dictates how quickly services must be restored from a backup (e.g., restoring service within 15 minutes). These metrics form the basis for backup scheduling and testing.
📅 Retention policies specify how long backups must be kept (e.g., one year or lifetime retention), often driven by the need to trace historical transactions or logs spanning several years.
🔒 Backups must be encrypted to verify integrity and prevent unauthorized editing or access by malicious entities, adding a crucial layer of security.

3-2-1 Rule and Backup Tools
🧱 The industry standard is the 3-2-1 Rule: maintain three copies of the data, store copies on two different media types, and keep one copy offsite to protect against site-specific disasters like fire.
🛠️ System administrators commonly use file system level backup tools such as `tar` for files, directories, and consistent database dumps.
🔄 Backups should combine full backups (copying all data) and incremental backups (copying only changed data) to create a complete system backup efficiently.

Backup Execution and Testing with `tar`
💻 The `tar` command syntax for creating a compressed archive is `tar czvf [output_file] [input_files/directories]`, where 'c' creates, 'v' is verbose (optional), 'z' compresses with gzip, and 'f' specifies the output file.
🧪 Test restores are mandatory; success is achieved when the restore process meets the defined RTO (e.g., completed in less than 5 minutes) and the recovered data matches the defined RPO (e.g., data within the last 5 minutes is restored properly).
🔍 Restoration verification involves checking file integrity—ensuring restored files can be opened and contain the correct, complete data.

Scheduling Backups using Cron
⚙️ Cron (the Linux equivalent of Windows Task Scheduler) automates background tasks at specific times, eliminating the need for manual execution during off-hours.
🗓️ Cron jobs are configured by editing the user's `crontab -e` file, where timing fields are specified in order: minute, hour, day of month, month, and day of week.
📉 Backups should be scheduled during periods of least transaction activity (e.g., 12:00 AM to 5:00 AM) to minimize strain on server resources (CPU, memory, disk I/O).
⭐ Automation commands in cron can be enhanced to include date and time stamps in the backup filename to easily distinguish new backups.

Key Points & Insights
➡️ System administrators must be proactive by defining clear backup policies covering scope, RPO, RTO, and retention before implementation.
➡️ Always follow the 3-2-1 Backup Rule (three copies, two media types, one offsite) to ensure disaster resilience.
➡️ Use the `tar czvf` command structure to create compressed archives and `tar zxvf -C /path` to test restoration to a specific directory for verification.
➡️ Automate scheduling using `crontab -e` during times of low server load to ensure consistency and adherence to the defined backup schedule.

📸 Video summarized with SummaryTube.com on Jan 09, 2026, 11:32 UTC