What is Tier 4 Data Center: definition
Tier standards define the level of availability of the Data Centers. Tier I is the basic level that is non-redundant, unable to cope with failures or hotfix requirements. In such cases, the level of failure could lead to several dozen hours of unavailability over the course of a year. Conversely, the highest level, Tier IV, is highly resistant to potential failures. Only Tier IV, which is called “fault-tolerant” can, through the redundancy of its equipment, come close to “zero failure” level and therefore offer close to 100% availability.