Lecture no 22: Computing Centers

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Lecture no 22 Computing Centers
TDT4285 Planlegging og drift av
IT-systemer Spring 2007 Anders Christensen, IDI
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Planning of computing centers

• Air circulation
• Air conditioning
• Signal cabling
• Raised floor
• Markings
• Communications
• Console servers
• Area for work on HW
• Tools

• Location
• Physical access
• Security
• Electrical power
• Power cabling
• Ventilation
• Fire extinguishing
• Racks

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Location

• Usually in a cellar
• Preferably not too much sun
• Must have some physical protection
• Needs lots of infrastructure
• Should be taken into account when planning the
  building
• Usually more difficult and expensive to retro-fit

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Physical access and security

• To obtain security
• As few doors and windows as possible
• Every point of entry should be controlled
• Must have control over who gets access
• For access
• Loading docks for trucks
• Lifts of sufficient size and capacity
• Width and height of doors
• Removable thresholds for all doors.

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Power supply

• Eletrical power must be planned
• Partitioning in multiple circuits
• Location of circuit breakers
• Emergency power shutdown
• Power usage at startup and during normal
  operations
• Fast and slow fuses
• UPS (location, capacity, power requirements
  during reloading) ?
• Diesel generator

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Uninterrupted power supply
Signal to datacenter to initiate power down
UPS
Public power supply
Power to the Data center
Diesel generator (if relevant)
Batteries
Emergency Power cut
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Uninterruptable Power Supply

• Batteries have a finite life-time and must be
  changed
• Remember to connect lighting to the UPS
• Monitor the UPS for performance and capacity
• It is important to test the system and train the
  sysadmins
• Is the switching automatic (should be!)
• For how many minutes can the UPS supply the
  datacenter

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Power cabling

• Generally One cable to the rack, which is
  further distributed inside the rack
• Alternative solutions
• Outlets under the raised floor
• Outlets from rails under the roof
• Outlets from rails along the walls
• Fewer preplanned outlets needed if power is
  generally distributed inside the racks
• Rule you can never have too many power outlets
  and circuits.
• Consider special purpose computer outlets

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Ventilation

• Little need for changing the air
• Must have good air circulation
• May need to control air moisture
• Should filter to reduce dust problem
• Ventilation can help to lower temperatur, but
  this is usually not sufficient.

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Fire extinguishing

• Water easily damages equipment
• Halon is now phased out in Norway
• CO2 is efficient but potentially dangerous
• If fire, all equipment, including UPS should be
  turned off. (It is important to turn off fans
  that might blow smoke and dust through the
  machines.)

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Computer racks

• Usually 19 racks (height measured in U 1U
  1.75inch 4.445cm)
• Often useful with some infrastructure (power
  distribution or network switch) in the rack.
• Racks require rack-montable computers
• Computer chassis is more expensive
• Choose solutions that facilitates maintenance
• Rack solutions
• Sides, doors, back-doors, fans, power pads
• Brackets, blind panels, drawers,

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Air circulation

• Main principles
• Machines in through the front, out back
• Racks in through front (or bottom), out through
  back or top.
• Fan coils in through top, out down uner raised
  floor, or on floor level.
• Finding the optimal circulation
• Use a marker (smoke signal) and lots of
  temperature probes
• Experiment this is a complex system for which
  predictions are hard.

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Cooling

• Effect in KWatt (100 seldom achievable)
• Two types
• Passive ice water system with external cooler.
• Cooler with external, passive radiator
• Ice water means 10-12 C
• Cooling lowers the moisture

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Exemple air circulation
Cooler
Fan
Power
Front
Back
Closed ice water system
Radiator
Raised floor
19 rack
The water works
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Cabling

• Try to make cabling permanent
• Make cables with perfect lengths
• Use strips, not tape to fasten cables
• Do it nice and properly to maintain overview
• Any non-obvious cabling should be marked in both
  ends.
• Consider indirection through patch panels
• Use color coding to differentiate cable type and
  usage.

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Raised floor

• Consisting of tiles of 60x60cm
• Optional holes in the tiles give
• Supply cold air from under the floor
• Allows for cabling
• For large data centers every tile can be
  numbered (X,Y)
• If possible, let the relevant computer rooms have
  a lowered real floor, so that their raised
  floor is at same height as the rest of the
  buiding.

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Markings

• Two different objectives
• Against theft (ownership, un-erasable)
• Function (temporary, change when needed)
• Outdated markings must be removed.
• Markings must be
• Readable
• Consistent
• Avoid
• Permanent marking of temporary function
• Post-it notes, rubber bands and cheap tape (and
  other markings that will fall off)

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Console servers

• Have fewer screens than computers!
• Less power consumption and warmth
• Better usage of space
• Usually a better cabling solution
• Solution console consentrators
• Switches between different interfaces?
• How extendable are the solution?
• Access control?

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Communication

• Always have phones or other means of
  communication available
• Walkie-talkie or short range radio
• Non-mobile phones if extra long cables
• Door-bells outside controlled zones, and with
  loud alarms

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Work space

• A data center is not a suitable work space!
• Only use for short and infrequent periods
• Use ear protection (active or passive)
• Establish an operators room
• Protects from noise and low temperatures
• Suitable location for consoles
• Glass walls for visual contact with machines

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Tools

• Use a rolling cart with the necessary tools.
• Ensure order in the tools!
• All tools must be marked
• Every tool must have is specific location
• Prefer high-quality tools to cheap or multi-tools
• Possibility if the employees are unable to
  maintain order in the tools, give each a tool-set
  and require personal accountability for it.

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Some other things

• Accessibility for euro-pails
• Flash-lights for dark spots
• The location of documentation
• Local maps and diagrams
• Whiteboards for brainstorming