What are the 7 tiers of disaster recovery?

One blueprint for recovery planning describes a scheme consisting of six tiers of off-site recoverability (tiers 1-6), with a seventh tier (tier 0) that relies on local recovery only, with no off-site backup.

The tiers cover a full range of recovery options, ranging from no data moved off-site to full off-site copies with no loss of data. The following figures and text describe them from a CICS® perspective.

• Tier 0: no off-site data
  Tier 0 is defined as having no requirements to save information off-site, establish a backup hardware platform, or develop a disaster recovery plan. Tier 0 is the no-cost disaster recovery solution.
• Tier 1 - physical removal
  Tier 1 is defined as having a disaster recovery plan, required data set backups physically removed and transported to an off-site storage facility, and optionally, a backup site, but without the required hardware currently installed.
• Tier 2 - physical removal with hot site
  Tier 2, like tier 1, provides a very basic level of disaster recovery. You will lose data in the disaster, perhaps a considerable amount.
• Tier 3 - electronic vaulting
  Tier 3, like tiers 1 and 2, provides a basic level of disaster recovery. You will lose data in the disaster, perhaps a considerable amount of data.
• Tier 0–3 solutions
  Tiers 0 to 3 cover the disaster recovery plans of many CICS users. With the exception of tier 0, they employ the same basic design using a point-in-time copy of the necessary data. That data is then moved off-site to be used when required after a disaster.
• Tier 4 - active secondary site
  Tier 4 provides a more advanced level of disaster recovery. You will lose data in the disaster, but only a few minutes- or hours-worth.
• Tier 5 - two-site, two-phase commit
  A tier 5 solution is appropriate for a custom-designed recovery plan with special applications. Because these applications must be designed to use this solution, it cannot be implemented at most CICS sites.
• Tier 6 - minimal to zero data loss
  Tier 6 provides a very complete level of disaster recovery. You must assess whether the cost of achieving this level of disaster recovery is justified for your company.
• Tier 4–6 solutions
  This summary shows the three tiers and the various tools for each that can help you reach your required level of disaster recovery.

Parent topic: Disaster recovery

Businesses with a Tier 0 business continuity solution have no Business Continuity Plan. There is no saved information, no documentation, no Backup hardware, and no contingency plan. The time necessary to recover in this instance is unpredictable. In fact, it may not be possible to recover at all.

Tier 1: Data backup with no hot site

Businesses that use Tier 1 continuity solutions back up their data and send these backups to an off-site storage facility. The method of transporting these backups is often referred to as "PTAM" - the "Pick-up Truck Access Method." Depending on how often backups are created and shipped, these organizations must be prepared to accept several days to weeks of data loss, but their backups are secure off-site. However, this tier lacks the systems on which to restore data.

Tier 2: Data backup with a hot site

Businesses using Tier 2 business continuity solutions make regular backups on tape. This is combined with an off-site facility and infrastructure (known as a Hot Site) in which to restore systems from those tapes in the event of a disaster. This solution will still result in the need to recreate several hours or even days' worth of data, but the recovery time is more predictable.

Tier 3: Electronic vaulting

Tier 3 solutions build on the components of Tier 2. Additionally, some mission critical data is electronically vaulted. This electronically vaulted data is typically more current than that which is shipped via PTAM. As a result there is less data recreation or loss after a disaster occurs. The facilities for providing Electronic Remote Vaulting consists of high-speed communication circuits, some form of channel extension equipment and either physical or a Virtual tape library and an automated tape library at the remote site. IBM's Peer-to-Peer VTS and Oracle StorageTek Virtual Storage Manager (VSM) Clustering are two examples of this type implementation.

Tier 4: Point-in-time copies

Tier 4 solutions are used by businesses that require both greater data currency and faster recovery than users of lower tiers. Rather than relying largely on shipping tape, as is common on the lower tiers, Tier 4 solutions begin to incorporate more disk based solutions. Several hours of data loss is still possible, but it is easier to make such point-in-time (PiT) copies with greater frequency than tape backups even when electronically vaulted.

Tier 5: Transaction integrity

Tier 5 solutions are used by businesses with a requirement for consistency of data between the production and recovery data centers. There is little to no data loss in such solutions; however, the presence of this functionality is entirely dependent on the application in use.

Tier 6: Zero or near-zero data loss

Tier 6 business continuity solutions maintain the highest levels of data currency. They are used by businesses with little or no tolerance for data loss and who need to restore data to applications rapidly. These solutions have no dependence on the applications or applications staffs to provide data consistency. Tier 6 solutions often require some form of Disk mirroring. There are various synchronous and asynchronous solutions available from the Mainframe storage vendors. Each solution is somewhat different, offering different capabilities and providing different Recovery Point and Recover Time objectives. Often some form of automated tape solution is also required. However, this can vary somewhat depending on the amount and type of data residing on tape.

Tier 7: Highly automated, business integrated solution

Tier 7 solutions include all the major components being used for a Tier 6 solution with the additional integration of automation. This allows a Tier 7 solution to ensure consistency of data above that which is granted by Tier 6 solutions. Additionally, recovery of the applications is automated, allowing for restoration of systems and applications much faster and more reliably than would be possible through manual business continuity procedures.

What are the seven tiers of disaster recovery?

What is Tier 1 disaster recovery?

How many types of disaster recovery are there?

What are the disaster recovery methods?