8.3 Compute Backup & Recovery Design

Why This Topic Matters

This section answers the official skill "Recommend a backup and recovery solution for compute." Where Azure Site Recovery (previous section) answers "how do we fail over a whole running workload to another location," Azure Backup answers a different question: "how do we recover a virtual machine's data to a specific point in time after deletion, corruption, or a ransomware event?" AZ-305 scenarios test whether you can pick the right vault type and policy to hit stated retention, restore-speed, and cross-region requirements at a reasonable cost.

Vault Types: Recovery Services Vault vs. Backup Vault

For AZ-305 purposes, when a scenario says "back up Azure VMs," the Recovery Services vault is almost always the right answer; when it names disk-level or blob-level backup as a standalone need, the Backup vault is increasingly the modern answer.

Backup Policies: Standard vs. Enhanced

• Standard policy: one backup per day; instant-restore snapshots retained locally for 2 days by default (configurable 1-5 days) before the vault copy takes over.
• Enhanced policy: supports multiple backups per day (every 4, 6, 8, or 12 hours), required for zone-redundant/zone-pinned VMs, and retains instant-restore snapshots locally for 7 days by default (configurable 1-30 days).

Instant restore serves recovery requests directly from the local disk snapshot -- much faster than pulling data back from the vault -- so a scenario emphasizing fast restore of recent data should point you toward a shorter-interval Enhanced policy with a longer instant-restore snapshot window, not just "more retention."

Retention Hierarchy

Azure Backup retention is layered so you are not forced to keep every daily point forever:

All of these are configurable per policy. A scenario requiring "7 years of quarterly recovery points for compliance" is describing the yearly/monthly retention tiers, not a separate product.

Redundancy, Cross Region Restore, and Soft Delete

• Storage redundancy for the vault itself (LRS, ZRS, GRS) determines whether backup data survives a regional outage. Cross Region Restore (CRR) -- restoring a VM directly into the paired region -- requires the vault to use geo-redundant storage (GRS); it is unavailable with LRS or ZRS.
• Soft delete protects against accidental or malicious deletion of backup data (a key ransomware-resilience control): deleted backup items are retained in a soft-deleted state for a default recoverable window (commonly around 14 days) before permanent purge, and during that window an administrator can undelete the backup data.

Worked Scenario

A retail company runs order-processing VMs and states: "We need at least two backups per day, must be able to restore a VM into our secondary region if the primary region is unavailable, and we must be protected against an admin accidentally deleting the backup data." The design: use a Recovery Services vault configured with GRS, apply the Enhanced backup policy with a sub-daily schedule (e.g., every 12 hours), enable Cross Region Restore, and rely on the vault's default soft-delete protection. Each stated requirement maps to one specific configuration choice -- there is no single "enable everything" toggle, so the exam expects you to connect each requirement to its matching feature.

Common Decision Traps

• Choosing the Standard policy when the scenario requires more than one backup per day or zone-pinned VM support -- only Enhanced policy supports sub-daily schedules and zone-redundant configurations.
• Forgetting that Cross Region Restore requires GRS specifically -- picking LRS "to save cost" silently breaks a stated cross-region restore requirement.
• Confusing Azure Backup's point-in-time VM recovery with Azure Site Recovery's whole-environment failover -- a requirement to "keep the app running in another region during an outage" is ASR, not Backup, even though both use a vault.
• Treating soft delete as a backup strategy on its own -- it is a safety net against deletion, not a substitute for retention policy design.

Quick Recall Table