Backup for Databases & Unstructured Data

Database backup design

Azure SQL backup architecture

Backup Type	Frequency	What It Captures	Automatic?
Full	Weekly	Entire database	Yes
Differential	Every 12-24 hours	Changes since last full	Yes
Transaction log	Every 5-10 minutes	All transactions since last log backup	Yes

Recovery options

Azure SQL Recovery Options

Option	RPO	RTO	Scope	Best For
Point-in-time restore (PITR)	Seconds (log backup interval)	Minutes to hours	Same region	Accidental deletion, corruption — restore to any second
Long-term retention (LTR)	Weekly/monthly/yearly	Hours	Same or different region	Compliance — keep backups for years
Geo-restore	~1 hour (geo-replication lag)	Hours	Different region	Regional disaster — restore from geo-replicated backup
Active geo-replication	~5 seconds	Seconds	Different region	Low-RPO DR — readable secondary with fast failover
Auto-failover groups	~5 seconds	Seconds (automatic)	Different region	Automatic DR failover with read/write endpoint redirection

🏦 Elena’s SQL backup design:

• PITR retention: 35 days (maximum) for all production databases
• LTR: Weekly backups retained 52 weeks, monthly retained 12 months, yearly retained 7 years
• Auto-failover group: Trading database replicated to paired region with automatic failover
• Geo-restore: Enabled as a last-resort recovery option for non-critical databases

Cosmos DB backup

Cosmos DB Backup Modes

Factor	Continuous Backup	Periodic Backup
Restore granularity	Any point in time (last 7 or 30 days)	Specific backup intervals (1-24 hours)
RPO	Seconds	Hours (interval-dependent)
Self-service restore	Yes — via portal/CLI	No — support ticket required
Cost	Included (7-day) or additional (30-day)	Included in Cosmos DB pricing
Best for	Production — accidental deletes, corruption	Non-critical — basic protection

Design recommendation: Always use continuous backup for production Cosmos DB accounts. The ability to self-service restore to any point in time is critical for operational recovery.

Unstructured data backup

Feature	What It Protects	How It Works
Soft delete	Accidental deletion	Deleted blobs recoverable for configured period (1-365 days)
Blob versioning	Accidental overwrite	Previous versions automatically retained
Point-in-time restore	Bulk corruption/deletion	Restore ALL block blobs in a container to a previous state
Azure Backup for Blobs	Operational + vault backup	Policy-driven backup with long-term retention in vault
Immutable storage	Malicious deletion/modification	WORM — cannot be deleted even by admins during retention

🏗️ Priya’s unstructured data backup:

• Soft delete: 30 days on all production containers
• Blob versioning: Enabled for document storage (track changes)
• Point-in-time restore: Enabled for critical containers (bulk recovery)
• GZRS redundancy: Cross-region durability for all production storage

Knowledge check

Question

What's the difference between Azure SQL PITR and geo-restore?

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Answer

PITR restores to any second within the retention window (7-35 days) in the same region — for accidental deletion or corruption. Geo-restore uses geo-replicated backups to restore in a DIFFERENT region — for regional disasters. Geo-restore has ~1 hour RPO (geo-replication lag) vs seconds for PITR.

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Question

What Cosmos DB backup mode should you recommend for production?

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Answer

Continuous backup — enables self-service point-in-time restore to any second within the last 7 or 30 days. Periodic backup requires a support ticket and has hours-level RPO. Always use continuous for production workloads.

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Question

What's the difference between blob soft delete, versioning, and immutable storage?

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Answer

Soft delete: recovers deleted blobs within a retention window. Versioning: keeps previous versions of overwritten blobs automatically. Immutable storage (WORM): prevents modification or deletion for a retention period — required for regulatory compliance. Use all three together: versioning for accidental overwrites, soft delete for accidental deletions, immutable storage for compliance.

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Knowledge Check

🏦 Elena's compliance team requires Azure SQL database backups retained for 7 years. They also need the ability to restore to any second within the last 35 days for operational recovery. Which combination should Elena configure?

APITR with 35-day retention onlyBLong-term retention (LTR) with yearly backups for 7 years onlyCPITR with 35-day retention AND LTR with yearly backups retained for 7 yearsDActive geo-replication with 7-year retention

Check Answer

Knowledge Check

🏛️ David's government client stores legal documents in Azure Blob Storage. Regulations require that documents cannot be modified or deleted for 10 years after upload. Staff must still be able to read documents at any time. Which storage feature should David configure?

ABlob soft delete with 10-year retentionBBlob versioning with a lifecycle policy to retain all versions for 10 yearsCAzure Backup for blobs with 10-year retention vaultDTime-based immutable storage policy with 10-year retention at the container level

Check Answer

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