Tier 3 Data Center: Why Is It the Right Choice for Most Businesses?
In the summer of 2023 one of our e-commerce customers called: "There has been a power cut — are the systems down?" We checked: no, they were not. The generators had kicked in automatically and the customer did not even notice. That is what Tier 3 is like. You do not notice when it happens to you, because the infrastructure is designed to prevent it. But is every data center like this? Definitely not.
The Tier System: The DNA of Data Centers
In the 1990s the Uptime Institute developed the Tier system to classify data centers according to objective criteria. Accepted worldwide today, the system consists of 4 levels:
| Feature |
Tier 1 |
Tier 2 |
Tier 3 |
Tier 4 |
| Uptime Guarantee |
%99.671 |
%99.741 |
99.98%2 |
%99.995 |
| Annual Downtime |
28.8 hours |
22 hours |
1.6 hours |
0.4 hours |
| Power Path |
Single |
Single |
Multiple (1 active) |
Multiple (2 active) |
| Downtime During Maintenance |
Yes |
Yes |
No |
No |
The figures matter, but what really matters is what they mean in day-to-day operations. An example: with 99.982% uptime an e-commerce site is offline for only 1.6 hours a year. 99.671% (Tier 1) means 28.8 hours. If you suffer 4 hours of downtime on Black Friday, the difference is felt very clearly.
Tier 3's Magic Feature: Concurrent Maintainability
The most critical feature that sets Tier 3 apart from the others: Concurrent Maintainability (the ability to carry out maintenance while everything keeps running).
A Real Scenario: In May 2024 UPS maintenance was due. In a Tier 2 data center this means shutting down all the servers. At SistemDC (built to Tier 3 standards), customers noticed nothing. Why? Because the UPS on the first power path was taken into maintenance while the second path was active. The systems kept running.
The Anatomy of a Tier 3 Infrastructure
1. Power System (N+1 Redundancy)
Utility Power A → UPS A → PDU A → Server Rack
↗
Utility Power B → UPS B → PDU B → (Backup line)
↗
Generator (N+1) → UPS C →
In SistemDC's data center, built to Tier 3 standards:
- 2x 2.5 MVA transformers (dual utility feed)
- 4x 1250 kVA generators (N+1 configuration)
- 48 hours of fuel capacity
- UPS systems: N+1 redundant
2. Cooling System
In Tier 3, cooling is redundant too:
- 8x Precision Cooling Units - N+1 redundancy
- Hot Aisle / Cold Aisle design - airflow optimization
- Free Cooling - natural cooling in the winter months (energy savings)
- Ideal conditions: 20-25°C temperature, 40-60% humidity
PUE (Power Usage Effectiveness) is the ratio of a facility's total energy consumption to its IT load. A range of 1.4–1.6 comes up in industry discussions; this is a general figure, not a documented PUE value for SistemDC.
3. Network Infrastructure
Tier 3 is not just about power and cooling; the network is critical too:
SistemDC Network Architecture:
- AS211804: Our own BGP autonomous system number
- 3 Upstream ISPs: Turk Telekom, Vodafone, TTNet
- BGP routing: Automatic failover (if one ISP goes down the others carry on)
- 10 Gbps+ total bandwidth
Tier 3 vs the Others: Which Business Should Choose What?
Tier 1 - Basic Capacity
Who it is for: Test environments, hobby projects, low-criticality applications
- ❌ No redundant systems - there is a single point of failure
- ❌ Servers are shut down for maintenance
- ❌ 28.8 hours of downtime per year
- ✓ Low cost
Tier 2 - Redundant Components
Who it is for: SMEs, mid-sized websites, in-house applications
- ✓ Some components are redundant (UPS, cooling)
- ❌ Downtime is required for maintenance
- ❌ 22 hours of downtime per year
- ✓ Mid-level cost
Tier 3 - Concurrently Maintainable (SistemDC: built to Tier 3 standards)
Who it is for: E-commerce, SaaS, gaming, business applications
- ✓ Multiple power and cooling paths
- ✓ No downtime during maintenance
- ✓ 99.982% uptime (1.6 hours per year)
- ✓ Reasonable cost
Tier 4 - Fault Tolerant
Who it is for: Banking, telecommunications, national critical infrastructure
- ✓ 2N redundancy (fully duplicated systems)
- ✓ No single point of failure
- ✓ 99.995% uptime (26 minutes per year)
- ❌ 60-70% more expensive
A Real Cost Comparison: Does a Tier 3 Investment Make Sense?
In 2022 one of our customers moved to us from a Tier 2 data center. The reason: they had lost 180,000 TL in revenue during a 6-hour power cut.
| Scenario |
Initial Investment |
Annual Operation |
5-Year Total |
| Your Own Tier 1 Data Center |
2,000,000 TL |
400,000 TL |
4,000,000 TL |
| Colocation built to Tier 3 standards (SistemDC) |
0 TL |
96,000 TL |
480,000 TL |
| Cloud (AWS/Azure) |
0 TL |
180,000 TL |
900,000 TL |
SistemDC Colocation Pricing:
- 1/4 Rack (10U): 2,500 TL/mo
- 1/2 Rack (21U): 4,500 TL/mo
- Full Rack (42U): 8,000 TL/mo
Included: 3 kW of power, 33 TB transfer, Tier 3 infrastructure, 24/7 support, remote hands
Tier 3 Certification: On Paper or for Real?
There are many "Tier 3" claims on the market, but few Uptime Institute certificates. Why? Because certification is a serious process:
Uptime Institute Certification Stages
1. Design Review
- Architectural plans are examined in detail
- Electrical diagrams are verified
- The cooling design is tested
- Cost: $30,000 - $50,000
2. Constructed Facility
- Site visits
- Installation checks
- Commissioning tests
- Cost: $25,000 - $40,000
3. Operational Sustainability
- Procedure audits
- Staff training programmes
- Maintenance plans are reviewed
- Annual renewal: $10,000 - $15,000
Caution: Many data centers in Turkey say "Tier 3 ready" or "Tier 3 equivalent". This is not a certificate, only a claim. Very few data centers actually hold a genuine Uptime Institute Tier 3 Certification.
SistemDC Istanbul: colocation built to Tier 3 standards
SistemDC was founded in Bursa in 2012; its registered office is still in Bursa. Server colocation and rack rental are delivered from the data center in Istanbul, built to Tier 3 standards. This article makes no claim of Uptime Institute certification.
For shared rack space (1U–4U / ATX), see the server colocation plans; for a private rack (10U–42U), see the rack rental page.
Which Businesses Should Choose Tier 3?
Tier 3 Is Definitely Required:
- E-commerce sites: Every hour means lost revenue
- SaaS companies: They have customer SLAs
- Gaming servers: 24/7 availability is critical
- Finance applications: PCI-DSS compliance is required
Tier 1-2 May Be Enough:
- Test and development environments
- Low-traffic websites
- Archive servers
- Internal network file servers
Conclusion: Why Is Tier 3 the Right Balance?
Tier 3 strikes an excellent balance between cost and reliability. It is the right choice if:
- 99.98%+ uptime is your target
- Downtime is costly for you (e-commerce, SaaS)
- You have no Tier 4 budget
- You do not want to shut servers down for maintenance
In 2024 one of our customers said: "I have been with you for 3 years and never had a power cut. Is Tier 3 really this good?" Yes, it is this good. Because that is exactly the point of Tier 3: the customer does not notice.
Note: The technical details in this article were prepared with reference to the Uptime Institute's publicly available Tier definitions. The customer experiences are real; names are withheld for confidentiality.
Turkey (Türkçe) 
