Backup and Restore: Periodic vs Continuous

Backup: your safety net

Marcus’s backup strategy

⚙️ Marcus at FinSecure handles financial data with strict RPO (Recovery Point Objective) requirements:

• Transaction database: RPO = 0 seconds (continuous backup, 30-day retention)
• Analytics database: RPO = 4 hours (periodic backup, cost-effective)
• Compliance requirement: All restores must be to a new account for audit isolation

Periodic backup

The default backup mode. Cosmos DB takes full snapshots automatically:

Setting	Options	Default
Interval	1-24 hours	4 hours
Retention	2× interval to 720 hours (30 days max)	8 hours (2 copies)
Redundancy	Locally redundant, Zone-redundant, Geo-redundant	Geo-redundant

# Configure periodic backup
az cosmosdb update --name finsecure-cosmos \
  --resource-group rg-finsecure \
  --backup-interval 60 \
  --backup-retention 168 \
  --backup-redundancy "Geo"

Key limitations:

• Cannot self-restore — you must contact Azure Support for periodic backup restore
• RPO = backup interval (if interval is 4 hours, you can lose up to 4 hours of data)
• Backups are stored separately and don’t consume your account storage

Continuous backup

Continuous backup enables point-in-time restore (PITR) — restore to any second:

Feature	Continuous 7-day	Continuous 30-day
Retention	7 days	30 days
Restore granularity	Any second within window	Any second within window
Self-service restore	✅ Yes (portal, CLI, SDK)	✅ Yes
Cost	Included (no extra charge)	Additional charge per GB/month
Restore target	New account or existing account	New account or existing account
Multi-region writes	Supported	Supported
Migration from periodic	✅ Supported	✅ Supported

# Enable continuous backup (30-day) on a new account
az cosmosdb create --name finsecure-transactions \
  --resource-group rg-finsecure \
  --backup-policy-type Continuous \
  --continuous-tier Continuous30Days

# Point-in-time restore
az cosmosdb restore --name finsecure-restored \
  --resource-group rg-finsecure \
  --target-database-account-name finsecure-transactions \
  --restore-timestamp "2025-07-15T10:30:00Z" \
  --location "eastus"

💡 Exam tip: restore options for continuous backup

Continuous backup supports restoring to a new account or to an existing account (for restoring deleted containers/databases). Periodic backup restore always creates a new account and requires contacting Azure Support. Key details:

• Restoring to an existing account is preferred for deleted containers/databases (avoids data transfer cost)
• Restoring to a new account is preferred for accidental data modification scenarios
• The original account remains untouched when restoring to a new account
• Throughput settings, indexing policies, and stored procedures are restored
• The restored account gets a new name that you specify (for new account restores)

The exam may test this distinction — know that continuous backup now has both options, while periodic always needs a support ticket and new account.

Periodic vs continuous comparison

Aspect	Periodic Backup	Continuous Backup
RPO	Backup interval (1-24 hours)	~0 seconds (any timestamp)
Self-service restore	❌ Contact Azure Support	✅ Self-service via portal/CLI
Granularity	Full snapshot at interval	Any second within retention
Retention	Up to 30 days	7 or 30 days
Extra cost	None (included)	None for 7-day; extra for 30-day
Restore target	New account	New account or existing account
When to use	Cost-conscious, relaxed RPO	Mission-critical, near-zero RPO

🎬 Video walkthrough

🎬 Video coming soon

Backup and Restore — DP-420 Module 23

Backup and Restore — DP-420 Module 23

~14 min

Flashcards

Question

What is the key difference between periodic and continuous backup?

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Answer

Periodic takes snapshots at intervals (1-24 hours) with data loss up to the interval. Continuous enables point-in-time restore to any second within the retention window (7 or 30 days). Continuous has near-zero RPO.

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💡 Show hint

Question

Where does a Cosmos DB restore go?

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Answer

Continuous backup supports restoring to a NEW account OR to an EXISTING account (for restoring deleted containers/databases). Periodic backup always restores to a new account via Azure Support. The original account is untouched when using the new-account option.

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💡 Show hint

Question

Can you self-service restore from a periodic backup?

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Answer

No — periodic backup restore requires contacting Azure Support. Continuous backup supports self-service restore via the Azure portal, CLI, or SDK. This is a key difference the exam tests.

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💡 Show hint

Question

What is the cost difference between 7-day and 30-day continuous backup?

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Answer

7-day continuous backup is included at no extra charge. 30-day continuous backup has an additional charge per GB/month of stored data. Both provide point-in-time restore granularity.

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💡 Show hint

Knowledge Check

Knowledge Check

Marcus's transaction database requires near-zero RPO and the ability to restore without contacting Azure Support. Which backup mode should he choose?

APeriodic backup with 1-hour intervalBContinuous backup with 30-day retentionCPeriodic backup with geo-redundant storageDNo backup needed — Cosmos DB is multi-region

Check Answer

Knowledge Check

A developer accidentally deletes a container at 2:15 PM. The account uses continuous backup with 30-day retention. What's the restore process?

ARestore the container in-place from the Azure portalBRestore the deleted container into the existing account or create a new account, specifying a timestamp before 2:15 PMCContact Azure Support to restore the containerDRecover from the change feed since deletes are captured

Check Answer

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Next up: Network Security — firewalls, VNets, private endpoints, and CORS for securing access to your Cosmos DB account.