Understanding the 7 Tiers of Disaster Recovery

Companies implement disaster recovery plans to help them bring their operations back online as quickly as possible when the most unexpected circumstances occur. These unforeseen events can be as diverse as natural disasters like earthquakes, fires, or hurricanes, as well as cyberattacks or incidents caused by human error.  

The diverse nature of these disasters means that organizations must create a disaster recovery plan that aligns with their operations. They should, therefore, familiarize themselves with the different tiers of disaster recovery so they can craft a recovery plan that will optimize their business resilience. This guide explains the seven disaster recovery levels and how each fits into your IT recovery planning. 

Tier 0: No Off-Site Data 

Tier 0 is the ground level of disaster recovery planning. At this level, organizations have no off-site data recovery plan and keep all their stored data on-site. These organizations often back up their data with magnetic tape or disk drives, as companies did in the 1960s–1980s.  

While the upfront costs may be less for a tier 0 disaster recovery system (on-prem storage costs can still be prohibitive), organizations that use this recovery model are most at risk if a disaster happens. Natural disasters may make it impossible to recover some data, causing disaster recovery times to be indefinite — and may even cause some businesses to shutter.  

Tier 1: Physical Backup With a Cold Site 

Unlike tier 0, tier 1 disaster recovery plans use an off-site facility. These physical backup sites lack any IT hardware or other equipment needed to resume business operations. Third-party providers often supply these "cold sites" and provide the physical storage space, HVAC, electricity, and basic connectivity necessary to keep backup data secure. The client must provide any IT equipment that would be used for disaster recovery. 

Tier 1 disaster recovery models offer more security than tier 0 models, but the downtime may still be lengthy. Once a natural disaster strikes, for example, organizations must still purchase new hardware and have it shipped to the cold site before they can resume operations. This could take over a week, and given the cost of operational downtime, that expense is simply too great.   

Tier 2: Physical Backup With a Hot Site 

While tier 1 involves physical backup with no IT equipment, tier 2 disaster recovery uses off-site physical backup, complete with the hardware required to continue your business processes. These "hot sites" can take over most of an organization's operations should a disaster event occur, as the third-party provider will have already furnished the site with the IT assets needed for a complete recovery.  

Because hot sites already possess the equipment needed to resume operations, recovery time objectives (RTOs) — the target time it will take to restore operations — are on the order of days rather than weeks. However, because they still use physical backup, the restore point will be the most recent time of physical data transfer. This makes tier 2 models acceptable for some non-critical data, but items requiring more frequent backup will need a more advanced model. 

Tier 3: Electronic Vaulting 

Instead of transporting physical storage devices to hot sites as tier 2 models do, tier 3 models electronically transfer the data to the off-site location. Storage devices used in this tier include hard drives, tape drives, and optical storage, which is made possible by greater network bandwidth and faster transmission speeds.  

While saving on physical storage costs, this tier requires greater investment in connectivity. Its main advantage is that it allows for more frequent backup so that organizations can return to a more recent restore point in their operations. Recovery time is typically less than one day.  

Tier 4: Point-in-Time Recovery With Copies or Active Secondary Site 

The tier 4 disaster recovery strategy employs a point-in-time recovery method. Such systems save their data at the end of a given interval, often at the end of a business day. The saved data is then copied and sent to an active secondary site, with each site backing up the other. Storage mechanisms for tier 4 models include disk and solid-state drives and cloud storage technology. 

The secondary sites may be owned by either the company itself or a third-party provider, depending on which meets the organization's needs. A tier 4 disaster recovery model may cost more due to the need for increased storage capacity and more advanced storage technology. Still, it allows teams to move their recovery point objective (RPO) closer to the time that the disaster occurred. The time to recovery may depend on when the last point-in-time recovery occurred but is typically less than one day.  

Tier 5: Two-Site Commit/Transaction Integrity 

While tier 4 saves data at certain intervals, tier 5 recovery models save and transmit data to alternate sites continuously. This continuous backup approach requires substantially more storage space than the tier 4 model and is only made possible by the cloud. Organizations using this model will need to find a cost-effective cloud services provider, but the advantage is that they may recover their digital assets in less than one hour.  

Tier 6: Minimal to Zero Data Loss 

Tier 5 disaster backup recovery times may still be too long for organizations requiring a near-zero RPO, as those in the finance and banking sectors often do. Tier 6 uses disk mirroring and data replication technologies to achieve continuous data protection, letting companies access their disaster recovery data as soon as they can go back online.  

The enhanced data security provided by tier 6 disaster recovery offers allows teams affected by disaster to get back on their feet with minimal disruption. This boosts teams' efficiency and security at a time when they need it the most and gives them an edge over the competition. 

Tier 7: Highly Automated Disaster Recovery 

Instead of reactively backing up data like tiers 0–6, tier 7 proactively searches for system anomalies that could cause a disruption, backing up all necessary digital assets before an incident can occur.  

Tier 7 monitors your infrastructure's common vulnerabilities and exposures (CVEs) with artificial intelligence and compares your infrastructure's current state with a predetermined set of conditions to assess its overall health. If it detects a problem, it immediately backs up any predetermined assets so that you can maintain your operations. 

Plan for the Seven Tiers of Disaster Recovery To Restore IT Systems 

Without a comprehensive disaster recovery and business continuity plan, companies will struggle when catastrophes inevitably strike. A strategic IT disaster recovery plan is an essential component of your corporate resilience, and understanding the seven tiers of disaster recovery can help you build a pipeline that aligns with your operational needs.  

Dell Technologies helps organizations of all sizes advance their IT business goals, including helping them build a disaster recovery strategy. So, take advantage of these resources and bolster your company's disaster resilience today.