Designing the information system architecture, each company must determine the availability parameters of IT services according to the nature of its activities. In real life, this is the period representing the length of the information outage system for a certain period or a period during which IT services are unavailable. It does not have to be only a system failure, but may be a planned outage, maintenance, or reconfiguration of the system upgrade or innovation. As a rule, the IT user is not interested in this fact, his primary concern is the smooth operation of the system and that of the applications so that the normal business activities are not disrupted. When designing the required information system architecture, each company should define the period of unavailability of its information system so as to avoid the economic impact or financial losses resulting from the unavailability of the given information system. It is therefore necessary to consider the character and the type of company activities and thus what level of access to information system is inevitable for the company A different level of availability will be required by banking, stock exchange or other financial institutions, where even a short downtime of IT services can mean enormous financial losses. A different level of availability will be required, for example, by companies operating online shops or information portals. With these companies even several hours stoppage of IT services will not cause significant economic losses and reputation damages. The correct choice of the required degree of availability has a significant economic impact, it holds true that the higher the level of availability required, the higher the cost. When locating the companys IT into the cloud the required level of availability is defined in the contractual documentation as one of the essential parameters of the provided service. The parameters of provided services are anchored in the contract on SLA (Service Level Agreement) service where the provider of cloud services agrees to abide by all agreed parameters and at the same time, this agreement should define the sanction mechanisms in case of non-compliance with the agreed service and parameters level. Practical implementation of the provisions of the SLA contract clashes in practice with the weaknesses that hinder its strict observance. There is no precise and reliable mechanism or technology with which it would be possible to accurately measure access parameters of various provided cloud services. This is currently more about the responsible approach of cloud services providers to their customers and vice versa about the consumer´s confidence in cloud services provider.