Overselling versus Overloading: What Is Overselling? (Part 1)

What Is Overselling?

Overselling is a deprived way to define resource management on servers.

It applies to the disk space only. Specifically, it applies to the bandwidth, but in realism these days there are so many bandwidths available, that it does not matter the exterior of DDoS mitigation.

So let us use shared hosting (aka reseller hosting) as an example. There are four concepts to be considered:

  • Customers are buying a plan that has a space of X amount.
  • Customers are using the space of X amount.
  • Servers have the space of X amount.
  • Servers are regularly upgraded to new technology, which normally has more space.

Therefore, based on these key factors you have to manage the server: Does the entire allocation of space is used by the customer? In most cases, the reply is no. The average website comes under 1GB and acquires only modest traffic at best. To reserve the space of X amount constantly would be wastage; it would considerably drive up costs. And within that the reason for overselling lies: in retaining the costs down for customers.

To use some number from Stablehost — an outstanding host, that is very honest and transparent — a particular server might comprise 1200GB. Their $10 plan provides 20GB and permits 60 accounts per server which are not oversold (1200/20=60). The server may bring in $600 (10 x $60), which will hardly fulfill the costs of the server. Although a home desktop is economical, think of a server with multi-core Xeon CPUs, RAID-10 SAS server-grade hard drives, and 64GB+ of RAM is not. There are also energy charges to run them for 24/7, personnel costs for support, facility costs (co-location), bandwidth, etc. Therefore, that $10 wants to be like $30 or $40 to fulfill its costs!

Additionally, the server can only use a small portion of RAM and CPU, which is a total waste of resources. You’d be giving a high price for that thing you don’t use.

Abruptly overselling does not sound like a corrupt thing, does it?

Which Hosts Oversell?

All types of hosts oversell, period. Any shared/reseller host that says something else is either lying, or they are charging an expanse corresponding to having such a service. (i.e. about $4 per GB)

Sadly, almost all hosts hide these details from customers. They mostly refer to it as “trade secrets” or something similar gibberish. Mostly it is hidden because it is gone afar from mere overselling and entered the territory of overloading.

If you are a reseller host, it means you can do this using your reseller account. A simple check/tick box in cPanel permits the reseller to offer extra than that is available in their account. For example, a reseller of 20GB with 20 x 2GB plans (40GB = overselling). The disadvantage to this is the host is now one level removed as a provider, and too much overselling by the reseller can affect RAM and CPU on the server! Because of this fact, it takes a good host to provide dependable reseller hosting.

How Does Overselling Work?

The fundamental to “overselling” — or better, however (again!) clever resource management, this is what is — is to make a balance between server resources, including CPU and RAM, disk space availability, and average customer requirements. You need to be capable keep your promises to the customer while keeping charges in check.

Also, Stablehost has verified itself to be a truthful host, and has shared those values with us! For them, the magical number is 50%, and an accountable level of overselling is:

  • Not more than 600 customers (on average, it varies) per server. That is about 2GB each, on a server with 1200GB. It is more than double the average.
  • At least 50% of the CPU is idle, which permits for decent resources for all the sites.
  • At least 50% of the RAM is available, which again permits sites to use it as required. This comprises MySQL queries.

If at any time a site causes these amounts to drop, Stablehost will transfer that site to another server. (Except it is grown so large that it needs a VPS, but that is a different story for another time.)

It’s all about evaluating your hardware, evaluating your classic customer, and creating intelligent conclusions based on this data.

Unfortunately, many hosts do not do this — particularly the “unlimited” hosts such as Godaddy, Dreamhost, and the different EIG brands (Fatcow, iPage, PowWeb, etc). What happens there is you wind up with a server that is not just oversold but overloaded. It works slowly, gets postponed for using “too many resources”, and is unsatisfying to use. In our next part (part 2), we will examine What Is Overloading? , and which hosts are the usual offenders.

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