The seven tiers of disaster recovery - Plan4continuity Blog

The seven tiers of disaster recovery



One way to get any CEO or CFO sweating is to tell him that all the company data has been lost and cannot be recovered. That’s why data backup has become crucial to, and an essential part of business continuity. However, having a backup in place is not enough. This begs the question: how good is your data disaster recovery plan?


The volunteer user group known as SHARE came up with a concept to measure one's backup strategy and implementation. This concept is called the ‘seven tiers of disaster recovery’ This blog takes a closer look at these seven tiers and discusses the importance of ensuring that a watertight disaster recovery strategy is included in your arsenal against data loss.


Tier 0: No off-site data – virtually zero possibility of recovery

This means having no backup plan and – more disturbingly – no disaster recovery plan. The time to recover, if at all possible, is undefined. This is a very foolish and sadly widespread practice. Many companies only understand the importance of a data recovery solution after they have experienced some level of data-loss. Tier 0 is typically the area you want to avoid being categorized in, since it means that you are more than likely to lose unrecoverable data at some point.


Tier 1: Data backup without a hot site


Here data is backed up and transported to an off-site storage facility. If data were to be sent back, this could mean a delay of a few days or more. Tier 1 guarantees data redundancy, but doesn’t address the need to recover information within the shortest time possible. In today’s technology-rich era we live in, Tier 1 shouldn’t be considered unless limitations such as company budget or infrastructural shortcomings are influencing factors.


Tier 2: Data backup with a hot site


Companies using this system use tape backups. When needed, they make use of an alternate site, also called a hot site, where the data can be restored to. This could mean just a few hours of downtime. Keep in mind that tape backups are by far not the fastest data recovery medium. Although redundancy exists, the actual restoration period could be considerably long, thus impeding the business’ ability to continue functioning with minimal disruption.


Tier 3: Electronic vaulting


This solution uses Tier 2, but also makes use of VPN or secure networks, where data is constantly streamed to a remote location. Here the data to be backed up is preselected and consists of primarily mission critical data. These backups are more up to date than tape backups. When backing up over a WAN connection, it is important to provision for the bandwidth demands associated with moving large volumes of data over the wire.


Tier 4: Point in time copies

A point in time copy is where data is copied as a snapshot. This captures the data as one complete file. The use of hard drives is common in this tier and it is common for multiple backups to take place every day. Hard drives as a backup medium significantly increase backup and restoration time windows thanks to the read\write speeds they are capable of. Many businesses are now considering disk backups as a replacement to the much slower magnetic tape medium. With data repository sizes growing by the gigabyte, hard drives should be the medium of choice for business with massive storage requirements.


Tier 5: Transaction integrity


The integrity of data on the production and hot site locations is verified. This is done to eliminate any inconsistencies and data corruption. The manner in which this is done depends on the application or platform itself. Data is continuously transmitted to the hot site. Only mission critical data is typically transmitted here.


Tier 6: Zero or near zero data loss

Disaster recovery solutions in this tier maintain the highest levels of data accuracy (data being up to date). This involves having solutions in place that can restore applications rapidly and often involves disk mirroring with real-time data streaming. In the event of a server crash, switching to the hot-site can be done quickly with almost no interruption to the business.


Tier 7: Highly automated business-integrated solution


This is Tier 6 in advanced mode, with automation. This allows all the benefits of Tier 6 along with the advantage of automation. Sometimes downtime can be only a few minutes or seconds. Virtually no data loss occurs here.


So where does your business fit in the seven tier system?


The higher up on the tier system one goes, the less downtime and loss of data there will be. Assessing your continuity requirements should include identifying your most critical IT resources and prioritizing them in your continuity plan. Trimming the fat from your disaster recovery strategy won’t only streamline the backup process, but will also reduce the overall cost associated with securing your most important information assets. Continuity should be constantly re-evaluated to ensure that the right data is secured in the most operationally and financially efficient way. By doing so, moving your way up the disaster recovery tier ladder should be a less expensive and cumbersome process.


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