"99.99% guaranteed availability" — the line sits in the hero. Six months later, after four hours down on a Tuesday morning, support says it was non-counted planned maintenance, or a component outside SLA scope. Credit? Denied. That is not a difficult customer: it is the normal scenario when nobody read the exclusions annex.
An SLA is not a moral promise. It is a limited contractual compensation mechanism surrounded by conditions that drastically shrink eligible cases.
Anatomy of a hosting SLA
A typical SLA has four blocks:
- Metric — network uptime, panel, hypervisor, or specific service.
- Threshold — 99.9%, 99.95%, etc., calculated on calendar month.
- Compensation — credit as % of monthly invoice, rarely cash refund.
- Exclusions — the section that sometimes turns the guarantee into a slogan.
Marketing shows the threshold. Exclusions define reality.
Exclusions that keep coming back
| Frequent exclusion | Customer effect | Trap |
|---|---|---|
| Planned maintenance | Downtime hours not counted | Wide windows, late notice |
| Force majeure | External outage excluded | Very broad definition |
| Customer issue (config, code) | Your bug = no credit | Blurry line with infra incident |
| DDoS / attack | Mitigation = outside SLA | Real impact, zero compensation |
| Third-party / beta services | Product sold but no SLA | |
| Claim deadline | Ticket after 48h = void | Easy to miss in crisis |
A generous SLA on paper with ten exclusions is often worth less than a modest SLA on a clear, measurable scope.
SLA credits: why amounts stay symbolic
Even when eligible, compensation often caps at 5–15% of that service's monthly invoice — not lost revenue, not client penalties, not crisis labor.
Example: €8/month VPS, down 6 hours in a month. Max credit: €1.20. For a shop losing €2,000 margin, the SLA is a gesture, not insurance.
The summit: the guarantee covers what they choose to measure
That is what "99.99% uptime" comparisons omit: without alignment between SLA metric and user-facing probes, the number is decorative.
Decide and move forward without blind spots
Before signing, pull the SLA annex and highlight: exact scope, exclusions, maintenance window, claim deadline, credit cap.
Ask sales directly: "If my site is unreachable 4 hours on Tuesday, am I eligible for credit? Show me the clause."
For critical workloads, complement SLA with multi-region, tested backups, and incident runbooks — see our directory and comparator.
Frequently asked questions
Does a 99.9% SLA really guarantee availability?
Only on the defined contractual scope, excluding listed cases. Many SLAs cover provider network infrastructure, not your application instance or your own config mistakes.
How do you actually get an SLA credit?
Open a ticket within the deadline, prove downtime per the contract's measurement method, and often accept a very low monthly cap (5–15% of invoice).
Does planned maintenance count against the SLA?
Almost never. "Announced" windows can absorb hours of downtime with no credit — check maximum allowed duration.
Do you need a written SLA for a €5/month VPS?
Even at low price, the SLA defines what you can claim and what is excluded. Without reading exclusions, you believe you are covered for uninsured risk.
Next time someone guarantees "99.99%," ask for the exclusions PDF — not the banner.