- Azure provides more than 100 redundant & secure facilities worldwide linked with a network.
- You can pick the region and sometimes availability zone you want resources deployed into.
- Regions = Contains at least one, but often multiple datacenters that are nearby and networked together with a low-latency network.
- ?Some services or virtual machine features are only available in certain regions, such as specific virtual machine sizes or storage types.
- Azure regions as of February 2020:
- ??Regions provide better scalability, redundancy, and preserves data residency for your services.
- Read more: Azure regions
- For compliance or legal purposes.
- Azure Government
- China East, China North and more
- Each region belongs to a single geography
- Defined by geopolitical boundaries or country borders.
- Has specific service availability, compliance, and data residency/sovereignty rules applied to it
- Fault-tolerant to withstand complete region failure through their connection to dedicated networking infrastructure
- Data residency
- Geographies are broken up into the following areas
- Read more: Azure geographies
- ?? Physically separate datacenters within an Azure region.
- ?? Allows you to make applications highly available through redundancy.
- Have independent power, cooling, and networking
- Set up to be an isolation boundary
- Identified as 1-2-3
- Connected through high-speed, private fiber-optic networks.
- ?There are regions that do not support (multiple) availability zones
- Each Azure region is always paired with another region within the same geography
- Pairs are at least 300 (≈ 500 km) miles away.
- Allows for the replication of resources, e.g. virtual machine storage
- Reduce the likelihood of interruptions to both regions
- If one region fails, services automatically fail over to the other region in its region pair.
- Data continues to reside within the same geography as its pair (except for Brazil South) for tax and law enforcement jurisdiction purposes.
- If there's an extensive Azure outage =>
- Planned Azure updates are rolled out to paired regions one region at a time to minimize downtime and risk of application outage.
- Formal documents to define the performance standards that apply to Azure.
- Specify also what happens if a service or product fails to perform to a governing SLAs specification.
- There are SLAs for individual Azure products and services.
- ? Azure does not provide SLAs for most services under the Free or Shared tiers
- Three key characteristics of SLAs for Azure products and services:
- Read more: SLA Summary for Azure Services
- Result of combining SLAs across different service offerings.
- ?? Calculating downtime
- You can improve the composite SLA by creating independent fallback paths.
- By creating your own SLAs, you can set performance targets to suit your specific Azure application.
- ?? >= four 9's (99.99%) SLA performance targets =>
- Resiliency is the ability of a system to recover from failures and continue to function.
- High availability and disaster recovery are two crucial components of resiliency
- Failure Mode Analysis (FMA)
- Read more: Designing resilient applications for Azure
- ?? Availability is often given as percentage uptime
- Refers to the time that a system is functional and working.
- Most providers prefer to maximize the availability of their Azure solutions by minimizing downtime.
- Read more: Availability choices for Azure compute
