Impact of Increasing “nofile” Limits in /etc/security/limits.conf

A Critical Linux Tuning Guide for Cloud, Hosting & High-Performance Infrastructure

In today’s always-on digital infrastructure, systems are expected to process tens of thousands—sometimes millions—of concurrent operations without interruption. Whether you’re managing cloud servers, enterprise hosting platforms, or high-traffic applications, small Linux kernel configurations can have an outsized impact on performance and reliability.

One such configuration is the “nofile” limit in /etc/security/limits.conf.

At Purvaco, we frequently see performance bottlenecks not caused by hardware or bandwidth—but by misconfigured OS-level limits. Increasing the nofile limit is one of the most overlooked yet powerful optimizations for modern cloud workloads.

What Is “nofile” in Linux?

The nofile limit defines the maximum number of open file descriptors a process or user can have at any given time.

In Linux, everything is treated as a file, including:

• Network sockets (TCP/UDP connections)

• Database connections

• Log files

• Pipes and IPC channels

• Actual files on disk

Each consumes one file descriptor.

Default Limits Are Too Low

Most Linux distributions ship with defaults like:

• Soft limit: 1024

• Hard limit: 4096

These values are not sufficient for modern workloads such as:

• High-traffic websites

• API gateways

• Databases

• Containerized microservices

• Cloud hosting environments

Why Increasing the “nofile” Limit Matters

1. Prevents “Too Many Open Files” Errors

A low nofile limit results in errors such as:

This can cause:

• Dropped connections

• Application crashes

• Failed database queries

• Service downtime

2. Enables Massive Concurrent Connections

Modern web servers like NGINX or HAProxy can handle 100,000+ concurrent connections—but only if file descriptor limits allow it.

Each active connection = 1 file descriptor

Without tuning, your application will hit a hard ceiling long before CPU or RAM limits.

3. Improves Database Stability & Throughput

Databases are among the largest consumers of file descriptors.

Recommended nofile values:

• MongoDB: 64,000+

• PostgreSQL: 10,000–100,000 (depending on workload)

• MySQL: High limits required for connection pooling

At Purvaco, database-related outages are one of the top issues resolved simply by raising nofile limits.

4. Essential for Cloud & Containerized Infrastructure

In cloud-native environments:

• Containers inherit host limits

• Kubernetes pods may fail silently

• Scaling breaks unpredictably

Without proper limits:

• Production behaves differently than staging

• Auto-scaling fails under load

• Observability tools stop logging

How to Configure “nofile” in /etc/security/limits.conf

To apply persistent system-wide limits, edit:

Recommended Production Configuration

This allows each user/process to open up to 65,535 files or sockets.

Other Places Where “nofile” Must Be Set

1. PAM Configuration (Critical)

Ensure limits are enforced:

Add:

2. systemd Services (Often Missed)

For services started via systemd:

Example:

Then reload:

3. Temporary Session Limits

⚠️ Not persistent across reboots

Real-World Cloud Hosting Scenario

Imagine a SaaS platform with:

• 10,000 daily active users

• 3–5 connections per session

• WebSockets + API + DB calls

That’s 40,000–50,000 file descriptors under load.

Without proper limits:

• New users are rejected

• Services restart randomly

• SLAs are violated

This is why Purvaco’s managed cloud and hosting solutions ship with pre-tuned OS-level limits, eliminating such risks before they happen.

Things to Watch Out For

Memory Consumption

Each file descriptor uses kernel memory. Ensure:

• Adequate RAM

• Proper monitoring

Security Considerations

Avoid unlimited values:

• Set per-user or per-service limits

• Monitor abuse using lsof and systemctl show

Legacy Applications

Some older apps may not scale linearly with high limits. Always test.

Best Practices Recommended by Purvaco

• Test changes in staging
• Monitor descriptor usage continuously
• Set limits in systemd, not just limits.conf
• Automate enforcement using Ansible, Terraform, or Puppet
• Document OS-level tuning in your DevOps pipeline

How Purvaco Helps

At Purvaco, we don’t just provide infrastructure—we engineer performance.

Our cloud and hosting environments include:

• Optimized Linux kernel parameters

• High nofile limits by default

• Database-ready server tuning

• Container-friendly configurations

• Proactive monitoring and alerts

So your applications scale smoothly without OS-level bottlenecks.

Conclusion: Small Limit, Massive Impact

Increasing the nofile limit in /etc/security/limits.conf may look like a minor tweak—but in modern cloud, hosting, and IT infrastructure, it’s foundational.

For high-traffic applications, distributed systems, and enterprise workloads, it can mean the difference between:

• Consistent uptime

• Random failures

• Seamless scaling

• Customer-visible outages

Don’t just go cloud—go cloud smart.
And that starts with knowing your limits—literally.

🚀 Ready to run infrastructure without hidden bottlenecks?

Purvaco delivers cloud hosting solutions built for performance, reliability, and scale.