What to Consider When Choosing a Data Center

Data center selection directly determines the reliability and performance of your server infrastructure. A wrong data center choice can lead to unexpected outages, data loss, and business continuity issues. This guide explains all the critical factors to consider when choosing a data center.

Tier Classification

The Uptime Institute classifies data centers into four Tier levels. This classification determines the reliability and uptime guarantee of the data center.

Tier 1 — Basic Infrastructure

Tier 1 Features:
- Annual uptime: 99.671%
- Annual downtime: 28.8 hours
- Power: Single path
- Cooling: Single path
- Maintenance: Requires downtime
- Use: Small businesses, test environments

Tier 2 — Redundant Components

Tier 2 Features:
- Annual uptime: 99.741%
- Annual downtime: 22 hours
- Power: N+1 redundant
- Cooling: N+1 redundant
- Maintenance: Partial downtime required
- Use: Medium-sized businesses

Tier 3 — Concurrent Maintenance

Tier 3 Features:
- Annual uptime: 99.982%
- Annual downtime: 1.6 hours
- Power: N+1 or 2N redundant
- Cooling: N+1 redundant
- Maintenance: Can be done without downtime
- Use: Enterprise applications, e-commerce

Tier 4 — Full Fault Tolerance

Tier 4 Features:
- Annual uptime: 99.995%
- Annual downtime: 26.3 minutes
- Power: 2N+1 fully redundant
- Cooling: 2N fully redundant
- Maintenance: Completely uninterrupted
- Use: Critical infrastructure, finance, healthcare

Tier Comparison Table

Feature	Tier 1	Tier 2	Tier 3	Tier 4
Annual Uptime	99.671%	99.741%	99.982%	99.995%
Annual Downtime	28.8 hrs	22 hrs	1.6 hrs	26 min
Power Paths	1	1+backup	2	2+backup
Cooling	Single	N+1	N+1	2N
Maintenance	Disruptive	Partial	Non-disruptive	Non-disruptive

Minimum Tier 3 is recommended for enterprise use. Tier 3 means only ~1.6 hours of downtime per year and is sufficient for most businesses.

Power Infrastructure

Power Redundancy Levels

N     → Single power source (minimum)
N+1   → One backup power source
2N    → Double copy of everything
2N+1  → Double copy + extra backup

UPS (Uninterruptible Power Supply)

UPS ensures servers continue to operate during grid outages.

Things to Check:
- Is UPS capacity sufficient?
- Battery age and maintenance status
- Automatic transfer time
- Is bypass mode available?

Generator

Generator Features:
- Fuel type: Diesel (preferred)
- Startup time: < 30 seconds
- Fuel capacity: How many hours?
- Automatic fuel replenishment agreement?
- Test frequency: Monthly testing?

Cooling Systems

Servers generate a lot of heat. Insufficient cooling leads to hardware failures and shortened lifespan.

PUE (Power Usage Effectiveness)

PUE = Total Facility Power / IT Equipment Power

PUE Assessment:
1.0:   Excellent (theoretical minimum)
1.2:   Very good
1.5:   Good
2.0:   Average
> 2.0: Inefficient

Hot/Cold Aisle Separation

Cold Aisle:  Front of servers (air intake)
Hot Aisle:   Back of servers (air exhaust)

Benefits:
- Prevents mixing of cold and hot air
- Increases cooling efficiency
- Saves energy

Physical Security

Access Control

Security Layers:
1. Perimeter security (fence, camera)
2. Building entrance (security personnel)
3. Data center entrance (card reader)
4. Rack room entrance (biometric)
5. Individual rack lock

Mantrap (Double Door System)

Mantrap Operation:
1. Person enters outer door
2. Outer door closes
3. Authentication is performed
4. If approved, inner door opens

Advantage: Prevents unauthorized entry

Network Connectivity

BGP and Multiple Upstream

Single Upstream (Bad):
Data Center → ISP A → Internet
Risk: If ISP A fails, all connectivity is lost

Multiple Upstream (Good):
Data Center → ISP A → Internet
             → ISP B → Internet
             → ISP C → Internet
Automatic load balancing and failover with BGP

Internet Exchange (IX) Connectivity

IX points are where different networks connect directly to each other. IX connectivity provides:

Lower latency
Better route diversity
Lower transit cost
Local traffic optimization

SLA and Compensation Policy

SLA Evaluation Criteria

SLA Checklist:
✓ What is the uptime guarantee? (99.9%, 99.99%?)
✓ How is downtime measured?
✓ Is planned maintenance included in SLA?
✓ What is the compensation rate?
✓ Is compensation automatic or does it require a request?
✓ What is the maximum compensation amount?
✓ What is the notification period?

REXE's TIER 3 Istanbul Data Center

REXE Technology serves from a TIER 3 certified data center in Istanbul.

REXE Data Center Features:

Tier Certification:
- TIER 3 certified
- 99.982% uptime SLA
- ~1.6 hours maximum downtime per year

Power Infrastructure:
- N+1 UPS system
- Diesel generator (72+ hours of fuel)
- Automatic transfer switch

Cooling:
- N+1 CRAC units
- Hot/cold aisle separation
- PUE < 1.5

Physical Security:
- 24/7 security personnel
- Biometric access control
- CCTV system
- Mantrap entry

Network Connectivity:
- Multiple upstream via Path.net
- Turkey IX connectivity
- BGP routing
- Tbps-capacity DDoS protection

Don't just look at price when choosing a data center. Tier certification, power redundancy, and network connectivity quality are much more important in the long run. REXE's TIER 3 infrastructure provides enterprise-level reliability.

What to Consider When Choosing a Data Center

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