backup and restore

**Backup and restore** is the practice of creating copies of **data, configurations, and system state** that can be used to recover from data loss, corruption, accidental deletion, or system failures. It is the most fundamental data protection mechanism. **What to Back Up in AI/ML Systems** - **Model Weights**: Trained model files — often tens to hundreds of GB. These represent weeks of compute investment. - **Training Data**: The datasets used for training, fine-tuning, and evaluation. - **Configuration**: System prompts, model configs, deployment manifests, feature flags, API routing rules. - **Vector Databases**: Embeddings and indexes for RAG systems — rebuilding from scratch can take hours. - **Application Data**: User conversations, feedback, evaluation results, usage logs. - **Infrastructure-as-Code**: Terraform, Kubernetes manifests, CI/CD pipelines, and environment definitions. - **Secrets**: API keys, certificates, and credentials (in encrypted backups). **Backup Strategies** - **Full Backup**: Complete copy of all data. Comprehensive but time-consuming and storage-intensive. - **Incremental Backup**: Only backs up changes since the last backup. Faster and smaller but requires the full backup chain for restore. - **Differential Backup**: Changes since the last full backup. Middle ground — faster than full, simpler restore than incremental. - **Continuous Backup (CDP)**: Every change is captured in real-time. Minimal data loss but requires more infrastructure. **Backup Best Practices** - **3-2-1 Rule**: Keep **3 copies** of data, on **2 different media types**, with **1 copy offsite** (or in a different cloud region). - **Automated Scheduling**: Never rely on manual backups — automate on a schedule (daily for most data, hourly for critical data). - **Test Restores Regularly**: A backup that can't be restored is worthless. Test restore procedures at least quarterly. - **Encrypt Backups**: All backups should be encrypted at rest and in transit. - **Retention Policy**: Define how long backups are kept — balance between recovery flexibility and storage costs. **Cloud Storage Options**: **AWS S3** (with versioning and cross-region replication), **Google Cloud Storage**, **Azure Blob Storage**, all with configurable lifecycle policies and storage tiers. Backup and restore is the **last line of defense** against data loss — when everything else fails, recent, tested backups are what save the organization.