Lecture no 22: Computing Centers

1. Lecture no 22: Computing Centers TDT4285 Planlegging og drift av IT-systemer Spring 2009 Anders Christensen, IDI TDT4285 Planl&drift IT-syst

2. Location Physical access Security Electrical power Power cabling Ventilation Fire extinguishing Racks Air circulation Air conditioning Signal cabling Raised floor Markings Communications Console servers Area for work on HW Tools Planning of computing centers TDT4285 Planl&drift IT-syst

3. 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 TDT4285 Planl&drift IT-syst

4. 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. TDT4285 Planl&drift IT-syst

5. 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 TDT4285 Planl&drift IT-syst

6. 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 TDT4285 Planl&drift IT-syst

7. 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 TDT4285 Planl&drift IT-syst

8. 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 TDT4285 Planl&drift IT-syst

9. 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. TDT4285 Planl&drift IT-syst

10. 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.) TDT4285 Planl&drift IT-syst

11. 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, TDT4285 Planl&drift IT-syst

12. 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. TDT4285 Planl&drift IT-syst

13. 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 TDT4285 Planl&drift IT-syst

14. Exemple: air circulation Cooler Fan Power Back Front Closed ice water system Radiator Raised floor 19’’ rack The water works TDT4285 Planl&drift IT-syst

15. 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. TDT4285 Planl&drift IT-syst

16. 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. TDT4285 Planl&drift IT-syst

17. 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) TDT4285 Planl&drift IT-syst

18. 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? TDT4285 Planl&drift IT-syst

19. 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 TDT4285 Planl&drift IT-syst

20. 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 TDT4285 Planl&drift IT-syst

21. 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. TDT4285 Planl&drift IT-syst

22. Some other things • Accessibility for euro-pails • Flash-lights for dark spots • The location of documentation • Local maps and diagrams • Whiteboards for brainstorming TDT4285 Planl&drift IT-syst