Disaster recovery service replicating VMs to a secondary site or region; recovery time is measured in minutes and recovery points are kept for no longer than 15 days.
Also called ASR, ASR, Site Recovery.
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains Azure Site Recovery in context, with comparison tables and the common traps.
Terms in this definition
- DR
Disaster recovery means getting a service running again from another region or site, with success judged by RPO and RTO; uptime SLAs and data retention are different concerns.
- Virtual machines
Infrastructure-as-a-service compute giving complete control of the operating system, making it a fit for lift-and-shift moves and for software relying on OS-level pieces like COM.
- LSDOU
The sequence in which Group Policy is processed: the local policy first, followed by site, domain and organisational unit policies. The nearest, last-processed setting takes effect unless Enforced or Block Inheritance alters that.
- region
A provider-defined grouping in VCF Automation of Supervisors that all share one NSX Local Manager; tenants consume its compute, storage and memory via quotas set per region.
Related terms
- Azure Backup
Azure's backup service, which keeps recovery points, long-term retention included, in a Recovery Services vault. It restores data rather than failing workloads over, which is the job of Site Recovery.
- Configuration server
Appliance that orchestrated replication of VMware machines for the older Site Recovery experience; you ran it on-premises, importing an OVF template into vSphere. Microsoft retired that classic approach in March 2026.
- Ephemeral OS disk
An OS disk held on the VM host's local storage instead of Azure Storage. It keeps no state across redeploys or resizes, can't be stopped and deallocated, and isn't supported by Azure Backup, Site Recovery or ADE.
- OVF
Short for Open Virtualization Format. VM templates are packaged to this open standard; one use is deploying Site Recovery appliances onto VMware vSphere.
- Recovery plans
Azure Site Recovery capability for automating failover, covering the grouping and sequence of machines and any scripts.
- Recovery Services vault
Where Azure Backup and Site Recovery keep their data; it offers soft delete, immutability and multi-user authorisation, but is the wrong choice for cheaply archiving files you already have.
- RTO
Recovery time objective, meaning how long you can tolerate a service being down before it is restored. Failing over with Site Recovery typically takes minutes; a restore from backup takes hours.
- Test failover
A Site Recovery rehearsal that spins up VMs in an isolated network while replication carries on. Each VM is placed in whichever target subnet shares its source subnet's name, failing that the alphabetically first one.