Azure Site Recovery
What it is
Azure Site Recovery (ASR) is Azure’s disaster-recovery (DR) service that replicates workloads (mainly VMs) to another region/site and orchestrates failover/failback so that if the primary region goes down, a replica can be brought online in the secondary region. It keeps a live copy running, not just historical snapshots.
Why it exists
Backup (the distinction) protects against data loss but doesn’t keep your app running. Site Recovery protects against region/site downtime — when the primary location is unavailable, you fail over to the replica and keep serving users with minimal downtime (RTO) and data loss (RPO).
Key ideas
- Replicates Azure VMs (Azure→Azure) or on-prem VMware/Hyper-V/Physical (on-prem→Azure) to a secondary region.
- Continuous replication into a Recovery Services vault; controlled by replication policy (RPO, snapshot frequency, recovery points).
- Test failover validates DR without disrupting production; failover switches traffic to the replica; failback returns to primary.
- RTO/RPO: Recovery Time Objective vs Recovery Point Objective — tuned via policy.
- Requires cache storage (staging) in source region, target resources in destination, and the vault.
How it fits (diagram)
Exam notes
- Site Recovery = DR replication (keep it running); Azure Backup = backups (recover deleted/corrupt data). This is a top distinction question.
- Enabled from the Recovery Services vault; uses a replication policy (RPO/retention).
- Test failover is how you validate DR safely; real failover + failback complete the cycle.
- Understand RTO (time to recover) vs RPO (max data loss between recovery points).
Related
azure-backup · recovery-services-vault · azure-vm · azure-backup-policy · Home
📘 Source: Microsoft Learn — Azure Site Recovery