Access to data and applications is critical for organizations that want to be productive and successful. On premise servers and workstations still play an important role for many of today’s small and mid-sized enterprises.
To understand today’s business continuity and disaster recovery requirements; it helps to look at the past. It wasn’t very long ago that back-up meant daily incremental and weekly full backups to tape or some other medium. Copies were created and shipped to a secondary location for disaster recovery. Many businesses continue to use this model today, and depending on your recovery needs, it may be perfectly adequate.
However, disaster recovery from tape or hard disk drive can be painfully slow. First, you need to retrieve the media from an off-site location. Once they are back on-premises, you must install your applications and restore your data.
Unfortunately, this could take considerable amount of time and lead to extended downtime.
When creating a business continuity plan for servers and workstations, it is important to understand two concepts:
Recovery time objective (RTO) is the amount of time that it takes to get a system restored following an outage. If a power supply on a server dies at 2 PM and you are able to replace the power supply and get the server back up and running at 5 PM your RTO would be 3 hours.
Recovery Point Objective is the point in time to which data can be restored following an outage. If you performed a backup at 6 PM, and a server failed at 5 PM the following afternoon, your RPO would be 23 hours and any data created during that span would be lost.
Modern business continuity solutions allow users to access data and applications from image-based back-ups of virtual servers and workstations. This capability dramatically improves RTO because operations can continue while primary servers are being restored. RPO is reduced as well as snapshot-based, incremental backups at short intervals are a common practice. Virtual machine images can also be replicated to an alternate site or the cloud in case of a physical disaster.