Ensure IT Availability: Plan Fail-Safe Systems Effectively 

In a digitized economy, the availability of IT systems has become critical to business success. Whether it’s an online store, cloud infrastructure, or production control system, outages result not only in revenue loss but also in damage to reputation and trust.

IT availability isn’t a matter of chance; it’s the result of deliberate decisions about priorities, technologies, and processes. The goal of this article is to provide a practical understanding of availability classes, causes of outages, and suitable measures to safeguard systems, enabling businesses to build a fail-safe, scalable IT landscape.

What is IT Availability?

IT availability refers to the ability of a system to reliably provide services, applications, or data during designated times without interruptions or unexpected outages. It is a central component of corporate IT strategies and a measurable factor within the framework of Service Level Agreements (SLAs), such as “99.9% availability per year.”

Unlike other aspects of IT security, such as confidentiality or integrity, availability focuses on operational status. Systems must not only be secured but also remain functional over time—for accessing cloud services, databases, or production controls.

Standards such as ISO/IEC 27001 classify availability as an equal priority protection goal. This means businesses must adopt specific measures to ensure that critical systems continue working under stress, failures, or external disruptions, or can quickly be restored.

Availability Classes Based on BSI Guidelines: Classification & Practical Relevance 

Not all IT applications require the same level of fail-safety, which is where availability classes (VK), such as those outlined in BSI guidelines, come into play. These classes help classify systems based on risks, ranging from low to high availability.

The classes range from VK1 (low requirements) to VK5 (highest availability):  

• VK1: For non-production systems like testing environments or internal tools without business relevance.
• VK3: For central services like email or ERP systems with moderate impact during outages.
• VK5: For systems with critical functions, e.g., energy supply, healthcare, or manufacturing, where every minute of outage counts.

Classification depends on factors such as: 

• Acceptable downtime (e.g., 1 hour or 5 minutes)
• Recovery time objectives
• Allowable data loss
• Business impact

For instance, an e-commerce shop might be categorized as VK4 since outages lead to lost revenue, while an automated production control system often requires VK5, as every second matters.

This categorization forms the foundation for targeted protection measures and should be an integral part of a Business Impact Analysis (BIA).

Typical Causes of Insufficient IT Availability 

IT outages are rarely due to a single cause; often, multiple factors interact simultaneously. A comprehensive understanding of potential weak points is essential to counteract systematically.

Common causes include: 

• Technical Failures: Such as hardware malfunctions, faulty storage components, unstable networks, or software bugs after updates.
• Human Errors: Misconfigured systems, accidental data deletion, or unclear responsibilities during incident management can lead to critical disruptions.
• Cyberattacks: Ransomware, DDoS attacks, or deliberate sabotage often result in significant availability issues, especially for inadequately protected endpoints.
• External Factors: Power outages, natural disasters (e.g., floods), or building damage from fires are rare but have severe consequences.

Particularly critical is the combination of several factors—for example, a lack of backups combined with user errors or an attack—which often results in longer recovery times and higher damages.

Understanding these causes is the first step, followed by implementing the appropriate technical, organizational, and personnel measures for mitigation.

Measures to Increase IT Availability 

High IT availability isn’t achieved by luck; it requires a planned approach combining technical redundancy, organizational processes, and preventive strategies. For MSPs and IT teams, this means not just reacting to disruptions but proactively avoiding them or minimizing their impact.  

Key Measures at a Glance:

• Redundancy Concepts: Building redundant networks, server clusters, or storage systems ensures automatic failover to alternative resources during disruptions.
• Backup & Disaster Recovery: Regular, automated backups and a tested disaster recovery plan guarantee limited data loss and rapid system restoration. Solutions like Cove Data Protection support geo-redundant data storage.
• Monitoring & Alerts: Continuous monitoring of critical systems with smart alert mechanisms allows for early intervention, ideally automated through tools like N‑central’s RMM solution.
• Regular Maintenance & Updates: Scheduled maintenance windows, patch management, and proactive resolution of known vulnerabilities reduce the risk of technical failures .
• Training & Awareness Programs: Employees are often unintentional sources of disruption. Regular training sessions help avoid errors and establish security standards.

Practical Example: A company combines virtualization with geo-redundant data centers, automated monitoring, and a coordinated recovery plan. Thus, even during a site failure, it can switch to backup systems within minutes, maintaining operations.

These measures should not be considered in isolation but as an integrated strategy that is regularly reviewed and enhanced.

Measurement & Verification: How IT Availability is Quantified 

To ensure that IT availability isn’t just a theoretical goal, it must be measurable and verifiable. Companies need clear metrics and targets, often defined within Service Level Agreements (SLAs).

Key Availability Metrics Include: 

• Availability Rate (%): Measures the percentage of time a system is operational.
• MTTR (Mean Time to Repair): The average time required to restore functionality after an outage.
• MTBF (Mean Time Between Failures): The average operational time between two outages.

Examples of Availability Targets: 

• 0% ≈ 87 hours of downtime per year
• 9% (“Three Nines”) ≈ 8.7 hours annually
• 999% (“Five Nines”) ≈ about 5 minutes annually

These targets vary by availability class—for instance, VK5 demands « Five Nines » availability, while VK1 allows greater flexibility. 

Monitoring systems frequently capture downtime, response times, and error rates. For MSPs, centralized control using an RMM platform enables analysis, alerting, and SLA reporting, making availability a concrete and measurable quality indicator. 

Strategically Planning and Securing IT Systems Availability 

IT availability isn’t a byproduct; it’s the outcome of strategically designed, technically secured, and organizationally anchored IT infrastructure. As businesses increasingly depend on digital processes, availability determines whether companies remain operational or risk revenue loss, data breaches, and damaged trust. 

For MSPs and IT decision-makers, ensuring high availability should be a core element of IT strategies, supported by defined availability objectives, aligned measures, and continuous monitoring. A combination of redundancy, backup strategies, proactive monitoring, and awareness forms the foundation.