Disaster recovery
Disaster recovery involves a set of policies, tools, and procedures to enable the recovery or continuation of vital technology infrastructure and systems following a natural or human-induced disaster. Disaster recovery focuses on the information technology (IT) or technology systems supporting critical business functions, as opposed to business continuity, which involves keeping all essential aspects of a business functioning despite significant disruptive events; it can therefore be considered a subset of business continuity. Disaster recovery assumes that the primary site is not recoverable for some time and represents a process of restoring data and services to a secondary  survived site, which is opposite to the process of restoring back to its original place. IT service continuity. IT Service Continuity (ITSC) is a subset of business continuity planning (BCP) that focuses on Recovery Point Objective (RPO) and Recovery Time Objective (RTO). It encompasses two kinds of planning; IT disaster recovery planning and wider IT resilience planning. Additionally, it also incorporates elements of IT infrastructure and services that relate to communications, such as (voice) telephony and data communications. Principles of backup sites. Planning includes arranging for backup sites, whether they are hot, warm, or cold, and standby sites with hardware  as needed for continuity. In 2008, the British Standards Institution launched a specific standard connected and supporting the Business Continuity Standard BS 25999, titled BS25777, specifically to align computer continuity with business continuity. This was withdrawn following the publication in March 2011 of ISO/IEC 27031 "Security techniques — Guidelines for information and communication technology readiness for business continuity". ITIL has defined some of these terms. Recovery Time Objective. The Recovery Time Objective (RTO) is the targeted duration of time and a service level within which a business process must be restored after a disaster (or disruption) in order to avoid  unacceptable consequences associated with a break in business continuity. According to business continuity planning methodology, the RTO is established during the Business Impact Analysis (BIA) by the owner(s) of the process, including identifying time frames for alternate or manual workarounds. Literature on the subject refers to RTO as a complement of Recovery Point Objective (RPO), with two metrics describing the limits of acceptable or "tolerable" ITSC performance. RTO and RPO gauges ITSC performance in terms of "time lost" from normal business process functioning and data lost or not backed up during that period (RPO), respectively. Recovery Time Actual. A Forbes  overview noted Recovery Time Actual (RTA) is, in fact, the critical metric for business continuity and disaster recovery. The business continuity group conducts timed rehearsals (or actuals), during which RTA gets determined and refined as needed. Recovery Point Objective. A Recovery Point Objective (RPO) is the maximum targeted period during which transactional data is lost from an IT service due to a major incident. For example, in the case, RPO is measured in minutes (or even a few hours), then in practice, off-site mirrored backups must be continuously maintained as a daily off-site backup on tape will not  suffice. Relationship to Recovery Time Objective. A recovery that is not instantaneous will restore transactional data over some time and do so without incurring significant risks or losses. RPO measures the maximum time in which recent data might have been permanently lost in the event of a major incident and is not a direct measure of the quantity of such loss. For instance, if the BC plan, to restore up to the last available backup, then the RPO is the maximum interval between such backups that have been safely vaulted off-site. It is often misinterpreted that RPO is determined  by the existing backup regime, whereas in reality, Business impact analysis determines RPO for each service. When off-site data is required, the period during which data might be lost often starts when backups are prepared, not when the backups are taken off-site. Data synchronization points. A data synchronization point is a point in time when physical data is backed up. It is one of the approaches used to halt the processing of an update queue, while a disk-to-disk copy is being made. The backup copy would reflect the earlier version of the copy operation; not when  the data is copied to tape or transmitted elsewhere. How RTO and RPO values affect computer system design. RTO and the RPO must be balanced, taking business risk into account, along with all the other major system design criteria. RPO is tied to the times' backups are sent offsite. Offsiting via synchronous copies to an offsite mirror allows for most unforeseen difficulty. The use of physical transportation for tapes (or other transportable media) comfortably covers some backup needs at a relatively low cost. Recovery can be enacted at a predetermined site. Shared offsite space and hardware complete the package needed . For high volumes of high-value transaction data, the hardware can be split across two or more sites by splitting across geographic areas adds resiliency. History. Planning for disaster recovery and information technology (IT) developed in the mid to late 1970s as computer center managers began to recognize the dependence of their organizations on their computer systems. At that time, most systems were batch-oriented mainframes. Another offsite mainframe could be loaded from backup tapes pending recovery of the primary site; downtime was relatively less critical. The disaster recovery industry developed to provide backup computer centers. One of the earliest  such centers was located in Sri Lanka (Sungard Availability Services, 1978). During the 1980s and 90s, as internal corporate timesharing, online data entry and real-time processing grew, more availability of IT systems was needed. Regulatory agencies became involved even before the rapid growth of the Internet during the 2000s; objectives of 2, 3, 4 or 5 nines (99.999%) were often mandated, and high-availability solutions for hot-site facilities were sought. IT Service Continuity is essential for many organizations in the implementation of Business Continuity Management (BCM) and Information Security Management (ICM) and as part of the implementation and  operation information security management as well as business continuity management as specified in ISO/IEC 27001 and ISO 22301 respectively. The rise of cloud computing since 2010 continues that trend: nowadays, it matters even less where computing services are physically served, just so long as the network itself is sufficiently reliable (a separate issue, and less of a concern since modern networks are highly resilient by design). 'Recovery as a Service' (RaaS) is one of the security features or benefits of cloud computing being promoted by the Cloud Security Alliance. Classification of disasters. Disasters can be the result of three  broad categories of threats and hazards. The first category is natural hazards that include acts of nature such as floods, hurricanes, tornadoes, earthquakes, and epidemics. The second category is technological hazards that include accidents or the failures of systems and structures such as pipeline explosions, transportation accidents, utility disruptions, dam failures, and accidental hazardous material releases. The third category is human-caused threats that include intentional acts such as active assailant attacks, chemical or biological attacks, cyber attacks against data or infrastructure, and sabotage. Preparedness measures for all categories and types of disasters fall into the five mission areas of  prevention, protection, mitigation, response, and recovery. Importance of disaster recovery planning. Recent research supports the idea that implementing a more holistic pre-disaster planning approach is more cost-effective in the long run. Every $1 spent on hazard mitigation (such as a disaster recovery plan) saves society $4 in response and recovery costs. 2015 disaster recovery statistics suggest that downtime lasting for one hour can cost As IT systems have become increasingly critical to the smooth operation of a company, and arguably the economy as a whole, the importance of ensuring the continued operation of those systems, and  their rapid recovery, has increased. For example, of companies that had a major loss of business data, 43% never reopen and 29% close within two years. As a result, preparation for continuation or recovery of systems needs to be taken very seriously. This involves a significant investment of time and money with the aim of ensuring minimal losses in the event of a disruptive event. Control measures. Control measures are steps or mechanisms that can reduce or eliminate various threats for organizations. Different types of measures can be included in a disaster recovery plan (DRP). Disaster recovery planning is a  subset of a larger process known as business continuity planning and includes planning for resumption of applications, data, hardware, electronic communications (such as networking), and other IT infrastructure. A business continuity plan (BCP) includes planning for non-IT related aspects such as key personnel, facilities, crisis communication, and reputation protection and should refer to the disaster recovery plan (DRP) for IT-related infrastructure recovery/continuity. IT disaster recovery control measures can be classified into the following three types: Good disaster recovery plan measures dictate that these three types of controls be documented and exercised regularly using so-called "DR tests . Strategies. Prior to selecting a disaster recovery strategy, a disaster recovery planner first refers to their organization's business continuity plan, which should indicate the key metrics of Recovery Point Objective and Recovery Time Objective. Metrics for business processes are then mapped to their systems and infrastructure. Failure to properly plan can extend the disaster's impact. Once metrics have been mapped, the organization reviews the IT budget; RTO and RPO metrics must fit with the available budget. A cost-benefit analysis often dictates which disaster recovery measures are implemented. Adding cloud-based backup to the benefits of local and 	Disaster recovery
26627260	offsite tape archiving, the New York Times" wrote, "adds a layer of data protection." Common strategies for data protection include: In many cases, an organization may elect to use an outsourced disaster recovery provider to provide a stand-by site and systems rather than using their own remote facilities, increasingly via cloud computing. In addition to preparing for the need to recover systems, organizations also implement precautionary measures with the objective of preventing a disaster in the first place. These may include: Disaster recovery as a service. Disaster recovery as a service (DRaaS) is an arrangement with a third party , a vendor. Commonly offered by Service Providers as part of their service portfolio. Although vendor lists have been published, "disaster recovery" is not a product, it's a service, even though several large hardware vendors have developed mobile/modular offerings that can be installed and made operational in very short time.