Similarly, in a real dedicated server, you will pay for the entire server that is not shared with anyone else. You will get complete control over all services. Unfortunately, it is also the most expensive hosting option and needs some technical expertise to manage. It is commonly used by those who have websites with specific scenarios, most commonly extremely high traffic and tight security requirements.
Essentially, here’s the criteria I would use to judge things – if your site is made up of primarily static, HTML-based content, then you probably don’t need a VPS package.  However, if you have a large amount of files stored, multiple sites, dynamic content, and the possibility of major traffic from time to time, then you might consider upgrading to a VPS. It’s a powerful package that allows you to do more than you could with a shared hosting plan, but requires less investment than a dedicated server.

And if your “neighbor” on the server is hacked, there’s little chance the infection will spread to your VPS because the hypervisors that are used to create separate VPS environments deliver multi-layered network security and keep tight controls on what enters and leaves. Your root access also means you can add or customize your VPS security software as you please.
Max Ostryzhko:

This means just a few domains could pull an entire reseller website offline if transfer limits are not closely monitored on a regular basis. Many Cloud VPS plans offer a "pay as you go" approach to billing where only the actual amount of CPU resources, storage, and I/O processes are billed. Systems administrators and website publishers need to calculate expected monthly traffic rates when estimating how many system resources are required to support a website in production. "Pay as you go" approaches can be more costly than fixed ratio accounts, where the trade-off is typically a more advanced VPS platform and toolset.

I can’t say it as a disadvantage of VPS hosting because many of our VPS hosting customers have server administrator to manage their VPS and they manage it in very efficiently manner. But this doesn’t everyone must have server administrator, we have content-rich knowledge base on VPS hosting for our self-managed customers.Also, a managed service option at very affordable price.
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