In a shared hosting environment, many customers' websites share the same servers and its resources. Some of these resources such as disk quota bandwidth, email e.t.c are enough to make your web site run successfully and we don't place hard limits on them,.
However, other resources are more crucial to the smooth running on of a shared hosting server and so we have to ensure one website isn't consuming all of a server's allocated resources; which can greatly affect the performance of the entire server thereby resulting in downtime; Hence we have resource usage "Limits" for CPU, RAM, I/O, inodes and Entry Processes for each hosting account on a General scale and for each hosting package as well. With Cloud Linux which helps us allocate server resources and ensures top performance hosting for all customers.
We will not explain each of these terms as you will see them on the left side of your cPanel area when you login
CPU - Central Processing Units
CPU represents the number of central processing units (CPUs) available to your account to process any requests. This ranges from loading data into RAM and processing scripts, to delivering content to visitors and writing into databases. Basically, your allocated CPU have serious effect on the rest your account's resources.
Because servers have multiple CPUs (also known refereed to as "Cores"), we display the percentage of the number of total cores your server can access.
When to Increase your allocated CPU
If you have a website that uses a database or relies on scripts, such as PHP, increasing your account's CPU will really enhance your website's performance. A few other things that make having access to additional CPUs beneficial are:
High volumes of traffic
Resource-intensive third-party add-ons, like themes and plugins
Outdated or poorly written code
Non-optimized PHP configuration
RAM - Random Access Memory
RAM is your Web server's most essential memory, which serves several purposes:
Website data loaded into RAM loads most quickly
Having more RAM prevents your CPU from having to retrieve data from the hard disk as often
Scripts that write to memory (e.g. PHP) will have more breathing room before they run out of space
Increasing a Web server's RAM means that it will work more quickly and can handle more complicated tasks.
When to Increase your RAM
Increasing your account's RAM limitation will increase your account's overall performance — so, if you want your website to be quicker in general, it's a good idea.
However, it's also compelling to increase your account's RAM when you know it's exceeding its limits and displaying 500 or 503 errors. However, exceeding your RAM limitation is often a symptom of an engineering problem and not the cause of the issue.
Exceeding your RAM limitation is often caused by a poorly configured plugin or script that floods the memory available to it. Increasing the RAM might improve the website's performance and stop it from generating errors, but it is possible that they will creep up again (even if it's less frequently). In this case, increasing the RAM further isn't the right solution - you need to fix the problematic element of your site.
That being said, you might also just have busy sites that are exceeding what their current limits can handle. Good news: increasing the RAM will solve these problems!
I/O - Input/Output
I/O stands for "Input/Output." In the context of a hosting account, it's the throughput or speed of data transfer between the hard disk and the RAM. Obviously, increasing the speed of transfer makes the process faster.
When to Increase I/O
Unlike some other limits, you don't really exceed your I/O limit and it doesn't generate errors. Instead, a site simply hangs while it waits for the data to transfer from the hard disk to the RAM.
Knowing when increasing I/O will improve a site requires knowing something about its entire construction. Generally speaking, sites that need to read and write a lot of data, such as those streaming any kind of media or with many database records, benefit most from I/O enhancements. However, increasing the I/O limit will not fix every issue that causes the site to lag or hang.
Files also known as Inode
File Usage counts the number of inodes on an account. An inode is more than simply a file — it's a piece of data that Linux-based systems use to reference a file or a directory. To make the arithmetic even trickier, you can also create multiple inodes that reference the same file or directory.
Roughly, though, you can say that the number inodes is the number of files plus the number of directories.
Another important distinction with our cPanel accounts is that each email a customer stores in their address counts as an inode — same thing for the folders they create to organize their email.
When to Increase Inode
If you need to store more files, directories, or emails on your hosting account, adding more inodes (via File Usage) is a simple way to make the problem disappear.
You may have some plugin or script that is creating an excessive number of files or directories on your accounts. In this case, increasing the File Usage probably will not resolve the issue; the runaway script or plugin might just fill the additional inodes available to it. Instead, you'll need to resolve the issue with the file itself.
Entry Processes are the number of connections your account can process simultaneously. Understanding what makes a connection is important, though, it's not as straightforward as "the number of visitors on your website." Below information constitutes what makes a connection:
Your website delivering data via HTTP
A Cron job processing
Your hosting account transferring data via SSH if available
Consequently, the connections are only counted while they are processing. As soon as they have finished, they no longer count as processes. As an example, if a visitor comes to your site and your home page takes .1 seconds to load and generates only one HTTP connection, that visitor counted as one process for .1 seconds. Even though that visitor is still "viewing your site," they no longer count as a connection until they do something else that generates another connection, like move to a new page.
When to Increase Entry Processes
As complicated as Entry Processes are to understand and calculate, it's incredibly easy to tell when you need more: when websites generate 508 (Resource Limit Reached) errors. Simply upgrading your account's Entry Processes makes those types of errors occur less frequently.
In general to upgrade any of these Server Resource require you to simply upgrade to higher package which will then give room for better performance, vBasic is usually the package at fault here as it is meant for low resource web site but somehow is used for hosting higher resource site by some client which is not supposed to, Vstandard and Vadavcned is highly recommend for better performance.