Instant recovery is a feature that allows a backup snapshot of a virtual machine (VM) to run temporarily on secondary storage after a failure or disaster occurs. Instant recovery may also be referred to as recovery in place.
One of the major hurdles in disaster recovery is the length of time it takes to recover and restore data from primary storage. Redirecting user workloads to a backup server while primary storage is being restored can improve the maximum tolerable length of time that an application can be down. Once the recovery has been completed, the workload is redirected to the original VM. Because the recovery occurs behind the scenes, the user is unaware that anything unusual has happened.
Although instant recovery doesn't require identical primary and secondary hardware to make the process work, it's important for adminstrators to test and make sure that backup hardware can support a production environment -- especially if the organization decides to use a relatively inexpensive option for secondary storage such as a cloud storage appliance.
See also: recovery time objective (RTO)