Placement Basics
Server colocation is typically for those who own their own server hardware and require complete control over the server configuration. Colocation specialists will host and connect a server they own to a fast Internet connection, usually in a secure data center, with 24/7 support.
It’s important to choose a colocation provider that has its own data center or has a presence in one of the major “data hotels.” World-class data centers are located in major industrial cities (New York, London, Frankfurt, for example). Here they can take advantage of the convergence of high-capacity network connectivity that occurs in a major shopping center. For example, fiber and metrolinks and ease of connection to the main points of presence (POPS) to the main telecommunications companies. For this reason, only a few of the leading ISPs or colocation specialists operate their own dedicated centers due to the costs of providing remote connectivity, redundant power sources, air conditioning, and clean filtered air.
Also, not all Internet connections are created equal. You really need to ask if your colocation specialist is “multihomed” using the BGP protocol by having at least two connections to tier one providers. Tier 1 providers are very large ISPs or telecommunications companies that operate their own fiber links and networks without having to operate traffic (or transit) through another ISP’s network. An example of a Tier One provider would be Tier 3 communications.
In addition to top-tier connections, the colocation specialist must have peering agreements at major exchange points, such as LINX. A peering point is where multiple ISPs arrange to “come together” to exchange traffic with each other instead of paying for transit through someone else’s network. In a way, they are “cutting out the middleman.” This not only improves redundancy but also reduces latency; People will be able to access the websites and content hosted on your colocated server much faster if your colo host is well interconnected.
Very often a web host or colocation ISP will negotiate many peering agreements with other ISPs with whom they exchange a large amount of traffic. This not only gives them more resiliency, but also lowers their own transit costs with tier one providers, allowing them to offer more competitive data transfer prices.
Latency is particularly important when it comes to game server hosting and placement. Very often, an ISP specializing in gaming hosting will give you an IP address so that you can test ping times and perform trace routes.
hardware options
Server hosting costs in London or New York can be high. Not surprisingly, your hardware needs to be “rack-optimized.” Colocation is generally priced “per U”. A “U” measures 1.75 inches (or 4.44 cm). Therefore, rack servers, unlike desktop machines, are long and flat. Data centers also employ different types of rack cabinets that are typically 42U high, enough to house 42 1U servers, although some of this space is used to accommodate switches and cabling. Some clearance is often left to allow efficient air distribution in the cabinet.
It is often worth contacting your color specialists about the choice of physical hardware and especially case and rack mounting. The placement specialist will know which brands work in your racks. I have personally found Dell’s rack-optimized servers and rail kits to be the fastest and easiest to install.
So you’ve decided on the hardware and you’re about to ship your server to the remote colocation data center. Keep in mind that your server will soon be hundreds of miles away; in fact, if you’re in the US, it could even be a few hours’ flight away, so there are a few technical points to consider before you pack, ship, and place the machine.
Make sure the operating system restarts
All colocated dedicated servers run “headless”. This means without the use of an attached keyboard or monitor. So you’ll need to make sure that servers get past the BIOS screen and boot the desired kernel without having to press any keys. It might be possible to configure the BIOS on your dedicated server to stop at “no errors”.
If you are running the Linux kernel, you will need to ensure that the correct kernel boots without intervention. This is usually determined by the settings in /etc/grub.conf if the GRUB bootloader is used, or /etc/lilo.conf if the LILO bootloader is used. After making any changes to the LILO configuration, remember to run “/sbin/lilo -v” and make sure there are no errors.
Also make sure that the kernel “works” correctly with the hardware. This is especially true if you have compiled the kernel yourself or are using specialized hardware.
Make sure the server is “Auto Powers” on
Most placement facilities provide an automated thermal cycler from a web interface. However, this can fail if the machine does not turn on automatically (requiring intervention by a technician). Most server BIOSes are equipped with “OFF”, “LAST STATE” or “ALWAYS ON”. In this case, it will require “ALWAYS ON”. It is possible to hack cheaper ATX motherboards to be “ALWAYS ON”, but it is better to consider a more expensive motherboard.
Network correctly configured
Make sure to properly configure the network addresses, DNS server, and gateways before delivery of the dedicated server. This information will have been provided in advance by the colocation provider. Also make sure you can get back to the server remotely by running the SSHD daemon (telnet is not secure).
OpenSSH ships with all major Linux distributions. You may want to consider configuring SSH (usually in /etc/sshd/sshd_config) to work only with Protocol 2, disable root logins (or only allow public key exchanges with the `without password`) and disable X11 forwarding as this is not needed on a production server.
Many servers have multiple Ethernet connectors, so it may be helpful, if you are not using the second interface, to mask it off with masking tape or label the correct Ethernet device.
Set up a serial console
This is sometimes called “out of band” management. Very often a colocation provider will have a serial terminal on site. This is basically a server on its own but with lots of serial ports. This allows you to connect to your server if the network has failed your server for some reason.
The most common serial port configuration is 9600 8n1 (we don’t recommend running it at a higher speed). If you are running a Red Hat Linux server, serial console access is usually configured in “/etc/inittab”. Try inserting the following line:
co:23456:respawn:/sbin/agetty ttyS0 9600 vt100
Cooling Considerations
Servers get quite hot mainly due to modern processors. Even in a fully air-conditioned environment. It will pay you to watch on the cooldown. Much will depend on rack density, however this is one more reason why you should consider a rack-optimized server, as air cooling should have been considered in a co-located environment. You can also familiarize yourself with the architecture of your motherboard chipset and consider installing “sensors”. You can then monitor your CPU and motherboard temperature and graph it using MRTG.
Cheap Colocation Providers
Well apart from us that is! However, the following London based colocation providers are highly recommended. In other words, they are in demand, they know what they are doing, and they have “leads.”
Bogons – http://www.bogons.net/ – Based on Telehouse, but can usually only be Sun Netra servers.
Black Cat Networks – http://www.blackcatnetworks.co.uk/ – Based at Redbus Harbor Exchange.
Jump Networks – http://www.jump.net.uk” – Also based in Telehouse North, Docklands.
Additional Thoughts
You may want to consider disk or hard drive redundancy. Although the “MTF” or “Mean Time To Failure” quoted by hard drive manufacturers is impressive, hard drive failures, especially IDE failures, occur with dismal frequency. With the advent of S-ATA drives there really is no excuse, especially if you’re on a budget. You should consider cheap S-ATA drives (if you can’t afford SCSI) with Linux software RAID.
It can be helpful to service technicians if all the main power lights are working. The power light, hard drive activity light, and network light can be very helpful. It goes without saying that the server should be properly labeled on the front end with its hostname and IP address so that it can be quickly identified.