Reliability with
Microsoft Azure
Building reliable systems on Azure is a shared responsibility. Microsoft
is responsible for the reliability of the cloud platform, including our global
network and datacenters. Our customers and partners are responsible forthe reliability of their cloud applications, using architectural best practices
based on the requirements of each workload.

Single VM

Local redundancies

Zonal redundancies

Regional redundancies

Improve the availability ofsingle-instance VMs by using
premium/ultra disks to qualify
for an availability SLA.

Protect against failures with redundancy withina single datacenter in the event of hardware
malfunctions or software update cycles.

Protect against datacenter failures throughredundancy within a single region in theevent of power, cooling, or networking issues.

Protect against entire-region failures with redundancy
beyond a single region in the event of a tornado,
earthquake, or other large-scale disaster.

99.9% SLA (3 9s)

VM availability (monthly)

Single VM

with premium/ultra disks

99.99% SLA (4 9s)

VM availability (monthly)

Availability Zones (2+ VMs)
within a region

Availability Set (2+ VMs)

Protect against the loss of an entire region
through asynchronous replication for failover ofvirtual machines and data using services likegeo-redundant storage and Azure Site Recovery.

Backup and restore

Replicate virtual machines and data to one ormore regions using Azure Backup, and conduct
self-service recoveries of Azure VMs or disks froma secondary region during an outage.

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Azure Site Recovery
Primary region

within a datacenter

Secondary region
Failover

Zone 1

Azure Site Recovery

Failback

Zone 2High availability

Disaster recoveryRPO and RTO

VM availability (monthly)

99.95% SLA (3½ 9s)

No matter what your service-level objectives are, Azure can help you
achieve your organization’s reliability goals. Design and operatemission-critical systems with confidence by taking advantage of built-infeatures for high availability, disaster recovery, and backup.

Maintain acceptable continuous performancedespite temporary failure in services, hardware, ordatacenters—as well as fluctuation in load—using
Azure Availability Zones and availability sets.

Industry-Leading

FailoverManaged Disk in Availability Set99.999999999% (11 9s)
Storage durability (annually)

Locally Redundant Storage(LRS)*
Virtual machine | Compute options

99.999999999% (11 9s)
Storage durability (annually)

Locally Redundant Storage (LRS)with Azure Managed Disks*

Storage account | Storage options
Optional: Azure Backup

Storage replication

Zone
Zone 33

99.9999999999% (12 9s)
Storage durability (annually)

Zone-Redundant Storage(ZRS)

Link

Failback

99.99999999999999% (16 9s)
Storage durability (annually)

Geo-Redundant Storage (GRS)*

Azure Well-Architected Framework
Build a resilient system in the cloud with apps architected for ahealthy state—resulting in no significant downtime and rapid
recovery from failures. Using the Azure Well-Architected Framework,
you can design highly reliable and resilient application architecturewith the help of industry-tested and proven guidance.

Learn more about the Azure
Well-Architected Framework.

Assess your workloads throughthe lens of reliability with theAzure Well-Architected Review.

Review the resilience checklist
for reliability considerations related
to individual Azure services.