For a professional host, organizing the space reserved for machines is of major importance. No matter what type of hosting, servers are systematically located in specialized hosting rooms called data centres.
A data centre is organized into bays, or cabinets that can house items on racks in spaces with a standardized width of 19 inches (48.26 cm).
One bay generally has an available space of 40U, 47U or 52U, where U designates the basic unit of height of each rackable element. 1U corresponds to a height of 1.75 inches (approximately 4.445 cm).
The explains why professional servers are in 19-inch rackable industrial cases.
Most network elements (switches, routers, firewalls, etc.) exist in 19" racks in 1U, 2U or 4U sizes. There are also sliding drawers containing a flat screen, keyboard and mouse that can be integrated into a 1U spot.
Choosing a Host
The allocated storage space, bandwidth and power of the server hosting the website are admittedly crucial but they are not the only factors that need to be taken into account when choosing a host.
Indeed, website unavailability or loss of data can prove to be very costly for businesses! Therefore, most host data centres offer server security guarantees:
- Security of physical access to the data centre thanks to access control (badge, magnetic or possibly biometric card) and a video-surveillance system linked to a permanent security department. In addition, the bays are locked with a system of padlocks equipped with intrusion detection mechanisms.
- Security against fires thanks to particle analysis fire detection systems (called VESDA for Very Early Smoke Detection Alarm) coupled with a gas fire extinguishing system. There are two gas based fire extinguishing methods:
- The emission of the gas halon 1301, which is now banned in many countries because of its toxicity
- The emission of an inert gas that is intended to stop combustion in bays by lowering the oxygen content in air: Inergen (N2 52%, Ar 40%, CO2 8%) or Argonite (N2 50%, Ar 50%)
- The emission of an inhibitor gas that is intended to prevent combustion: gas FM 200 (CH3HF7) or FE13 (CHF3)
- The misting of highly pressurised tiny drops of nitrogenous water less than 200 microns in diameter in order to cool down the combustion area
- Security of the Physical Environment: regulating the hygrometry (humidity level) and temperature with air conditioning, air extractors often placed above the bays and ventilators often installed below the bay
- Back-up power feeds, critical infrastructure (routers, air conditioning, etc.) and Internet connection lines, and the presence of inverters, and even generators
- A quality of service (QoS) guarantee as well as service restoration in cases of dysfunction (GRT: Guaranteed Repair Time).
In addition, hosts generally offer additional services that can prove useful or even essential:
- Remote reboot thanks to a power distribution unit (PDU), i.e. a system of electrical switches that can be controlled remoted via web interface. The switches generally used are APC MasterSwitch (APC is the acronym for American Power Conversion Corporation). This type of switch is generally equipped with a surge protector (SurgeArrest)
- Telephone request service to remotely restart a server. A passphrase and sometimes personal information are generally requested by the operator in order to verify the client's identity
- A filtering service, i.e. firewall, upstream of the bay
- A traffic monitoring service. Most of the time, the MRTG (Multi-Router Traffic Grapher) system is used. This system graphically charts the amount of traffic on the network lines
- Automatic back-up mechanisms