Depending on our Recovery Time Objective (RTO) and Recovery Point Objective (RPO), we can have 3 options for disaster recovery in SharePoint 2013, either cold, warm or hot. Let's see each one by one.
Cold Option: This is a complete manual option where you take backups of each of the components and restore them on a new environment. There is no extra licensing cost and hardware cost associated with this option and hence it is the cheapest. The RPO will be the last backup taken and RTO will be as slow as it gets the new environment to be up and running. Depending on cost vs. business impact this option can be used to manage recovery; normally recovery is in days rather than hours. You can take one initial backup and then an incremental backup every 2-4 hours. Regular exercise of creating a new environment with steps and scripts will help to make a new environment up and ready quickly. This is the slowest of all three options.
Warm Option: In this option, a duplicate standby environment is ready at the alternate location and is updated regularly using full and incremental backups of the primary environment. In this case there is an extra hardware cost involved unless a virtual hard disk image of production servers is kept up-to-date. With Windows Server 2012 creating virtual images is just a matter of a few clicks. This environment is ready with hardware, operating systems, application software and incremental updates. In case you go for virtual images, you must have an environment available in which you can easily configure and connect the images to re-create your production environment. The DNS configuration must be manually done to point to new the location. Depending on cost vs. business impact this option can be used to manage recovery within hours.
Hot Option: This is an instantaneous and complete automatic failover option of disaster recovery. It is the costliest option but the alternative environment is up within seconds. The SQL Server Always Availability ON option now makes this option possible for SharePoint as well. The duplicate standby environment is ready at the alternate location and is updated almost instantly either synchronously or asynchronously. If the two environments are geographically very apart (as shown below) then asynchronous update is the best option else the performance of the production system will degrade.
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Since the cost will be very high in the Hot option, only business-critical SharePoint applications are suggested and the remaining can use either warm or cold recovery options. With cloud being a new option, there is the possibility of a hybrid option, though in real life, since customizations cannot be done easily in the cloud, this option does not seem feasible for critical applications.
For a list of planning of service applications and other SharePoint farm components please refer to
here.