We are currently seeing IT in­fra­struc­tures shifting into the cloud as an in­creas­ing number of busi­ness­es choose to outsource their hardware resources and use a more flexible rental model. Spe­cial­ized web hosts offer a diverse range of models for private users and busi­ness­es alike, often es­tab­lish­ing them under new terms – but what lies behind it is not always such an in­no­v­a­tive concept.

More often than not, creative ideas coming out of the hosting sector might sound good in theory, but in practice leave users feeling perplexed. However, one of the marketing terms that gained greater pop­u­lar­i­ty in the course of ‘cloud­i­fi­ca­tion’ is the concept of the bare metal server. In this article, we explain the idea behind the bare metal server and what projects are suited to this web-hosting product.

Dedicated Servers
Per­for­mance through in­no­va­tion
  • Dedicated en­ter­prise hardware
  • Con­fig­urable hardware equipment
  • ISO-certified data centers

What is a bare metal server?

The term ‘bare metal’ suggests that this product is related to the physical side of web hosting – the hardware. In principle, a bare metal server is the very same concept as what was formerly known as a dedicated server, also known as a ‘single tenant server’. This is a computer in a hosting provider’s data center, whose resources are available to a single customer. This distances bare metal from tra­di­tion­al shared hosting products such as the virtual server, where multiple web projects are hosted within separate virtual machines on the same hardware basis.

Image: Schematic representation: dedicated vs. shared hosting
With shared hosting, several customers share one powerful physical machine, whereas a dedicated server allows the user to rely on a single, exclusive server.

There are many ad­van­tages to dedicated web hosting:

  • Root access: Unlike multi-tenant servers, bare metal servers are offered along with root access. With shared hosting, it is generally un­de­sir­able for a user to be able to make changes in the root directory of the shared hosting platform. Ad­min­is­tra­tion is therefore limited to project folders. The bare metal server, on the other hand, offers unlimited ad­min­is­tra­tion options. This grants users the greatest possible freedom when in­stalling software com­po­nents and server con­fig­u­ra­tion.
  • Dedicated hardware: Virtual machines on shared hosting platforms are largely in­de­pen­dent of each other. However, there is a chance that this hosting concept could the­o­ret­i­cal­ly cause a website to be affected by non-re­spond­ing scripts or vul­ner­a­bil­i­ties in other web projects on the same physical machine. Bare metal servers exclude dis­tur­bances of the per­for­mance and stability of a virtual server caused by neigh­bor­ing web projects – an effect known as the noisy neighbor effect. Only the server’s tenant has access to hardware resources such as hard disk space, CPU, and RAM.

Bare metal servers are primarily suited to a demanding web project with a con­tin­u­al­ly high re­quire­ment for resources. Projects that need to meet specific com­pli­ance re­quire­ments should also be hosted on dedicated hardware.

Bare metal server structure

The structure of a bare metal server is geared towards the user’s specific re­quire­ments. Es­sen­tial­ly, there are two varieties: tra­di­tion­al bare metal servers and bare metal servers with hy­per­vi­sor.

Note

A hy­per­vi­sor (also known as a virtual machine monitor or VMM) is a piece of software that enables the use of guest systems called virtual machines (VMs). Depending on the type of hy­per­vi­sor, the software is either based on an operating system (a hosted hy­per­vi­sor) or on the hardware for a native hy­per­vi­sor.  When it comes to bare metal servers, however, native hy­per­vi­sors are used. The hy­per­vi­sor com­mu­ni­cates directly with the physical machine without the need for an in­ter­me­di­ate server operating system.

  • Tra­di­tion­al bare metal server: Tra­di­tion­al bare metal servers are dedicated servers where the user-ad­min­is­tered operating system (OS) – such as Windows Server, Ubuntu, SUSE, Red Hat, Debian, or CentOS – relies on the hardware. All user ap­pli­ca­tions then run directly on the operating system. Tra­di­tion­al bare metal servers include both dedicated rental servers and self-hosted servers for companies within their own premises.
  • Bare metal servers with hy­per­vi­sors: Bare metal servers with hy­per­vi­sors can also be used in a cloud en­vi­ron­ment. This model is based directly on the hardware (native hy­per­vi­sor) and provides users with an ad­min­is­tra­tion interface for managing virtual machines. User ap­pli­ca­tions run sep­a­rate­ly in vir­tu­al­ized guest operating systems, rather than directly on the hy­per­vi­sor. Common hy­per­vi­sors are KVM, the native vir­tu­al­iza­tion feature of the Linux kernel, Microsoft Hyper-V, vSphere from VMware, or Citrix XenServer.

The following graphic shows a schematic rep­re­sen­ta­tion of both concepts:

Image: Schematic representation of a bare metal server, with and without a hypervisor
A bare metal server with a hy­per­vi­sor enables the operation of several guest systems

When the hardware resources of several dedicated servers are available to the user as part of a bare metal hosting, this is known as a bare metal cloud. The hosting product, bare metal, grants users extensive access rights to the server; while a shared hosting customer is limited to con­trol­ling a single virtual machine, the user-managed software component (OS or hy­per­vi­sor) of the bare metal server relies on the hardware. There is therefore no abstract level managed by the host between the hardware resources of the server and the user.

The most important product in the market of bare metal devices is the hy­per­vi­sor-based usage scenario. Through the user-driven vir­tu­al­iza­tion software, this hosting concept allows fast, simple supply of virtual machines. A bare metal server with a hy­per­vi­sor therefore offers a flexible al­ter­na­tive to the tra­di­tion­al dedicated server, which is often as­so­ci­at­ed with time-consuming manual con­fig­u­ra­tion.

What sort of projects are bare metal hosting products best suited to?

The bare metal server is primarily geared towards users that want to implement so­phis­ti­cat­ed web projects on a cus­tomized hosting platform. A server with dedicated hardware is rec­om­mend­ed for online shops and websites with con­sis­tent­ly high traffic. However, bare metal servers are also the preferred hosts for database and ap­pli­ca­tion servers with specific security re­quire­ments.

Root access allows in­di­vid­ual con­fig­u­ra­tion without com­pro­mise. Depending on the project in question, users can decide whether they want to allocate the server's hardware resources to a single operating system or whether they want to dis­trib­ute them across multiple systems using self-managed vir­tu­al­iza­tion software.

Like shared hosting packages, there are also different kinds of bare metal server available that offer various levels of per­for­mance. However, while the tra­di­tion­al virtual server primarily serves the mid-range price segment, the cost of providing dedicated hardware is usually reflected in higher costs. Bare metal is aimed at business customers and pro­fes­sion­al web projects. In­di­vid­u­als who run hobby websites or semi-pro­fes­sion­al web shops, on the other hand, are usually better off using shared hosting.

Note

A root server offers ex­pe­ri­enced ad­min­is­tra­tors extensive options to adjust software com­po­nents to in­di­vid­ual demands. This requires sound spe­cial­ist knowledge. Therefore, website operators who are un­fa­mil­iar with the technical side of web hosting should consider managed hosting instead of a bare metal server, as this allows the provider to take over the ad­min­is­tra­tion of the hosting platform.

Ad­van­tages and dis­ad­van­tages of bare metal servers at a glance

If you’re not sure whether the ‘bare metal’ hosting model is the optimal solution for your web project, consider this table of pros and cons:

Pros Cons
The server’s dedicated hardware is ex­clu­sive­ly available to one user Sound knowledge of server ad­min­is­tra­tion required
Root access enables in­di­vid­ual im­ple­men­ta­tion Higher cost than other hosting products
Operation of multiple guest systems using a user-managed native hy­per­vi­sor
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