In shared hosting environments, it's crucial to maintain server stability and performance. One of the most effective ways to achieve this is through the use of CloudLinux and Lightweight Virtual Environment (LVE) limits. This guide will provide an in-depth understanding of these technologies and how they contribute to a more stable and secure hosting environment.

What is CloudLinux?

CloudLinux is an operating system designed specifically for shared hosting providers. It improves server stability by isolating each client in a secure environment known as a Lightweight Virtual Environment (LVE). This isolation prevents a single account from monopolizing server resources and slowing down other accounts.

For instance, if one customer is using an unfair amount of resources due to a poorly written script or a DDoS attack, the server could become slow or even go down, affecting all other customers on the server. With CloudLinux, the impact is isolated to the offending tenant only, while all other sites remain unaffected.

Understanding LVE Limits

LVE limits are restrictions on the number of resources that can be consumed by a single user. These limits improve the general stability and performance of the server.

When an account reaches its resource limits, it will temporarily stop working until its resource usage returns to normal. Meanwhile, the other tenants on the server will continue to run normally.

For example, if an account is hitting CPU or IO limits, the site will begin to slow down. However, if it's hitting 'Entry Processes' (EP) or 'Memory' (PMEM) limits, the site will display a '503 Error'.

LVE 'Faults' and 'Snapshots'

When an account hits the LVE limits for a particular resource, we record something called a 'fault', along with a 'snapshot'. A fault is a recording of the resource type being hit, along with the time, date, and username. A snapshot is a list of processes running at the time of the LVE fault, allowing users to investigate why those limits are being hit.

CageFS: Enhancing Security

CloudLinux includes CageFS, a virtualized per-user file system that isolates each customer’s files and running processes. This prevents users from seeing each other and potentially exploiting sensitive information. CageFS offers complete isolation and prevents a large number of attacks, such as privilege escalation and information disclosure attacks.

Monitoring Resource Usage

You can monitor your account's resource usage at any time. Simply log into cPanel and look at the resource usage stats on the right-hand side. Resource usage is calculated relative to the limits applied to your account only, and not the entire server.

For example, if your account allows 2 CPU Cores and 2048 MB RAM, a CPU usage of 50% would mean that your account is currently maxing out 1 CPU Core. Memory usage of 50% would mean that your account is using 1024 MB RAM.

You can also check the 'CPU and Concurrent Connections' screen in cPanel for a more detailed overview.

By understanding and effectively managing CloudLinux and LVE limits, you can ensure a more stable and secure hosting environment for your website.