SV Group Solutions Disaster Recovery

Disaster Recovery

Implementation of continuous availability and the possibility of functioning of an information system in extraordinary circumstance (Disaster/Recovery)

The implementation of continuous availability and the possibility of functioning of the information system in extraordinary circumstances is a key factor for efficient and successful functioning of any institution or enterprise.

According to one study (Bush, Kugel from the University of Minnesota, USA), after a disaster 25% of the companies go bankrupt immediately, 40% of them go bankrupt within 2 years, and less than 7% manage to remain on the market.

System availability

The concept of system availability is described with three terms: high availability, continuous operation and continuous availability.

  • High availability

High availability is the property of a system to serve its users during a defined period of functioning with a satisfactory or an agreed service level.

The period of functioning, as well as the definition of ‘satisfactory’ service level is determined in the commitments of service providers or agreed between service users and service providers (SLA – Service Level Agreement).

Availability above 99.7% (26 hours of down-time in the entire year) is considered high availability; however, in present time there is a growing need for availability of 99.999% (5 minutes of down-time in the entire year).

  • Continuous operation

Continuous operation is the property of a system to provide services to users all the time, day and night, without planned downtime needed for system or data maintenance.

Obviously, it is very difficult to maintain or alter the system that is constantly working. A system may operate continuously without preventive maintenance, but its availability cannot be as high as it should, as it is subject to frequent unplanned downtime.

  • Continuous availability

Continuous availability is the property of a system to both possess high availability and operate non-stop. The system should be designed in such a way that its users are not aware of any planned or unplanned downtime.

This goal may seem unattainable, since hardware and software components are not available 100% and since they must be maintained. The solution, therefore, must contain hardware, software and procedures that will mask downtime to the user. Such a solution should enable rapid continuation of work after downtime so that the user does not even notice that downtime has occurred. The design and implementation of such a solution is not an easy task and entails considerable effort and material means.

Operating in extraordinary circumstances

How do we define downtime in the information system due to extraordinary circumstances?

This involves an unplanned occurrence (fire, flood, earthquake, sabotage, explosion, terrorist attack, electrical fault, collapse of a building, strike, computer error, disc subsystem error, human error, etc.), which results in a break of business functions over an unknown time period.

Continued work in extraordinary circumstances (disaster/recovery) is a procedure of enabling business functions from a back-up location.

The ratio between continuous availability and continued functioning in extraordinary circumstances

All the components that enable continuous availability of an information system are commonly placed in the same premises. In this manner, the premises themselves become a potential place of jeopardising system functioning. Therefore, regardless of the design of the continuous availability system, extraordinary circumstances (fire, flood, etc.) may cause a halt of the entire system. The solution must envisage the continuation of functioning from a back-up/alternative location.

What does successful continuation of functioning in extraordinary circumstances involve?

Figure 1 shows what successful continuation of functioning after extraordinary circumstances involves – it is much more than mere data copying.

In order for system functioning to be completely successful, all additional business functions (infrastructure, hardware, software, communications, applications, network administrators, management, programmers, operative) should be available.

It is clear from the above that continued functioning in extraordinary circumstances is not only a technical, but also a business solution.

Responsibility for a project 

Independently of many technical aspects involved, planning continuous availability and continued functioning in extraordinary circumstances is the responsibility of an organization/institution as a whole, and not primarily of the information system service. Namely, the reason for investing in a suitable solution is to improve overall business.

The decision about a suitable strategy for solving continuous availability and continued functioning in extraordinary circumstances may require:

  • Considerable investments and their feasibility (for example, new buildings, extension of communication links, additional information telecommunication resources, etc.)
  • Analysis of the importance and priority of individual business functions
  • Significant changes in the information ‘culture’ (new rules for application development, operative work, etc.)
  • Conscious acceptance of remaining risks (There is no 100% protection. Each solution is a kind of a compromise. The management must be aware of the remaining risks and must accept them explicitly).
  • Management support in the solution strategy

Therefore, although solution planning and implementation is primarily the task of IT experts, it still has to be initiated and guided from top management levels.

To implement the project SV Group Ltd. uses the following hardware/software components:

a)    Hardverske

  • IBM Servere (System z,  Power system, xServeri)
  • IBM Storage
  • SAN, LAN i DWDM uređaje

b)    Softverske

  • FlashCopy
  • PAV
  • XRC
  • PPRC
  • IBM Metro Mirror, Global Mirror
  • XRC Performance Monitor (5655-J23)
  • TDMF for z/OS
  • DFSMS (dss+hsm)
  • System Automation for z/OS
  • Tivoli NetView for z/OS
  • Tivoli Storage Manager – grupa proizvoda
  • DB2 UDB
  • TPC for Replication
  • GDPS

SV Group Ltd designs and implements projects of continuous availability and continued functioning of IT systems in extraordinary circumstances with the following content.

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