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17.1.3. pg 329

Machines in a datacenter should be ANY server machine that the SAs are to support, not just critical, HA, shared etc. The SA can not be expected to support a server that's sitting under someones desk and doesn't have a console connection nor a UPS nor proper backups nor...

Never allow the customer to have a server that's outside of the datacenter and then have them demand support. The SA team might do "best efforts" support on such a box, but the customer can't expect any SLA on such a machine.

17.1.4 pg 331

You might want to revisit the estimates of heat and power based on the newer high density blade farms. These take a lot more power and generate a lot more heat than traditional servers. An IBM bladeframe sounds like an aircraft because of the size and speed of fans it has to shift air through the frame.

A UPS scaling anecdote: A company was doing a full building refurbishment. This included a new datacenter, with UPS and conditioned power. The top of the building used to hold water; this was drained off and the void replaced with batteries. Lots of batteries. This was enough to power the datacenter and the whole floor of the building for four hours. Why four hours? Because at that point the emergency lighting would fail and so the building had to be evacuated. It was not possible for people to work from home, so they would shutdown the datacenter as the lighting failed. They didn't need a generator in this situation.

17.1.6 pg 343

Note rack stability. A number of racks may have additional feet that stick out into the aise. This is so that they can be balanced when servers on rails slid out and top topple forward. The foot can be a trip hazard!

pg 344 the debate on doors or not. Simple, glass doors! Actually there is a serious point about doors on racks; when open they block aisles, so you need to note that impact on free movement in the datacenter when people are working in a rack.

17.1.7 pg 349

Different colour cables can also be used for functional reasons (eg red for printers, blue for servers, black for interswitch/router connections, yellow for telephone/fax/ISDN, white for servers etc.

17.1.9 pg 356

Note that some places may not allow mobile comms in datacenters, especially now every phone contains a camera. Security. This may not matter too much for an SAs own datacenter, but if they have servers at a colo or off-site facility then beware.

-- StephenHarris - 18 Aug 2006

17.3 pg 367 Your ideal datacenter

I hope you've revised your idealness Fiber is a lot more important, as servers need SAN connections, preferabbly two, for redundancy. With the proliferation of 1U devices, it's possible to have 24 or 32 servers in a rack. That's 24 LAN connections, 24 Backup-network connections, 24 console connections... It's possibly worth rigging out some racks in preparation for this with their own switch/router and own console server in the bottom of the rack. Spread them through the datacenter to distribute heat loads.

Random point

Not sure where this should be in the chapter. It actually came to me when reading the Networks chapter. Anyway. It's important to pick a cabling standard and stick with it. If you want to do GigE^? over copper then flood wire for that and don't use GigE^? over fiber at all. Mixing fiber and copper for networking cables just increases complexity. So pick a corporate standard and stick with it.

-- StephenHarris - 21 Aug 2006