Pio2pio: Created page with "Two important aspects of resiliency are high availability and disaster recovery. ;High availability (HA): is the ability of the application to continue running in a healthy st..."

2018-11-17T18:53:04Z

Created page with "Two important aspects of resiliency are high availability and disaster recovery. ;High availability (HA): is the ability of the application to continue running in a healthy st..."

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Two important aspects of resiliency are high availability and disaster recovery.
;High availability (HA): is the ability of the application to continue running in a healthy state, without significant downtime. By "healthy state," we mean the application is responsive, and users can connect to the application and interact with it.

;Disaster recovery (DR): is the ability to recover from rare but major incidents: non-transient, wide-scale failures, such as service disruption that affects an entire region. Disaster recovery includes data backup and archiving, and may include manual intervention, such as restoring a database from backup.

One way to think about HA versus DR is that DR starts when the impact of a fault exceeds the ability of the HA design to handle it.

;Business continuity (BC): which is the ability to perform essential business functions during and after adverse conditions, such as a natural disaster or a downed service.

Systems resiliency
Two important metrics to consider are the recovery time objective and recovery point objective.
;Recovery time objective (RTO): is the maximum acceptable time that an application can be unavailable after an incident. If your RTO is 90 minutes, you must be able to restore the application to a running state within 90 minutes from the start of a disaster. If you have a very low RTO, you might keep a second deployment continually running on standby, to protect against a regional outage.

;Recovery point objective (RPO): is the maximum duration of data loss that is acceptable during a disaster. For example, if you store data in a single database, with no replication to other databases, and perform hourly backups, you could lose up to an hour of data.

= Resources =
*[https://docs.microsoft.com/en-us/azure/architecture/resiliency/ Designing resilient applications for Azure] Microsoft Docs

Disaster recovery, HA, RTO, RPO - Revision history

Pio2pio: Created page with "Two important aspects of resiliency are high availability and disaster recovery. ;High availability (HA): is the ability of the application to continue running in a healthy st..."