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Just some quick questions on colocation and what things to look out for.

When looking for a colocation facility, what are things I should be looking for? What are the differences between a cheap facility and a high end one?

PS. how many servers can you git in a 1/4, 1/2 or full rack? i.e. I guess how many U's? since I might have a mix of 1u and 2u servers potentially.

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5 Answers 5

what should you look for? well - it all depends; from the top of my head:

  • unlimited 24x7 access to the facility without additional fees [ for the locations that are near place where i live ]
  • availability of 24x7 staff at the datacenter able to help you with remote hands; check the rates before signing the contract, expect prices of 100-200E/hour if you dont sign up premium maintenance contract
  • method of billing for bandwidth - most often 95th percentile + minimum commited rate, but recently i'm billed based on monthly average,
  • methods of billing for electricity [ flat - eg: 64Amps @ 220V, based on actual usage in kWh, based on maximum provided power + actual usage ],
  • information how redundant datacenters power supply, hvac and network connections are [ but in fact you learn about it when things go down ].
  • sla level - what discounts do you get when things go wrong; definition of measuring sla parameters.
  • availability of 3rd party connectivity providers on-site - if you plan to use BGP and want to peer with other ISPs.
  • own power supply from diesel engine, A+B power supply provided to your rack [ that is from two independent sources - eg two different UPS'es ]

cheap facility might:

  • not have staff in-place 24x7,
  • not be helpful when dealing with DDoS attacks,
  • provide power from one source [ eg via single ups ], instead of two independent lines,
  • charge you for:
    • calling the support outside business hours [ even if you report poblems with internet connectivity provided by them ],
    • too frequent visit at the facility.
  • provide less physical security / isolation between tenants
  • have less available bandwidth on the peering connections to handle peak load
  • be incompetent [ the worst of all ]

one rack is usually between 42U - 46U. some data centers might want to reserve top or bottom level for their own power distribution units or network patchpanels.

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PS. how many servers can you git in a 1/4, 1/2 or full rack? i.e. I guess how many U's? since I might have a mix of 1u and 2u servers potentially.

The number of machines you can get in a rack will usually be constrained by the power they consume (and the associated cooling) not the physical space. Too many people don't bother to check how much power their servers use then they get surprised when their rack is labelled 'full' when it doesn't look full.

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High-end facilities come with added features and services available, as well as various certifications which may increase their trust as well as allow you to host certain things inside their facility (HIPAA for medical data).

Any facility you choose should have N+1 redundancy on power, cooling and Internet connectivity.

You can fit 42 units (42 1U servers, for example), but this varies as there are racks which have more than 42U space.

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pQd's answer covers the majority of the basics, so I won't repeat all of that here. Another thing to look at is the general cleanliness of the facility. How did they do their wiring? Is it neat and tidy or are there messes of cables all over the place? Is the data center area clean and swept up or is there debris on the floor around the racks (cuttings from cat5, wire ties, etc)? Do they have redundancy in their network; a/c; battery backup; generators; fire suppression? Where is their power emergency cut-off and would it be easy for someone to accidentally bump into or is it well protected? Does their gear appear to be data center grade equipment or did they throw it together on the cheap (rack mounted, metered, power distribution bars or do they have consumer grade power strips hanging behind the rack?)

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pQd covered it all really well, so im not really adding too much. One thing I would recommend is speaking to some current customers - also check for any bad reviews online.

Check out the network. Who are the upstream providers (make sure they have are more than one!) and who are the upstream providers? What kind of bandwidth do they have coming into the building (DS3, Fiber, Etc) and are these connections coming in through physically diverse paths? How much bandwidth do they have access to? The more connected they are, the better off you are when it comes to data transport between you and your clients, employees, etc. You would be surprised at the number of colocation facilities operating on a single connection.

I agree with #pQd - ask about bandwidth billing - make sure you know what your getting into.

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