Tips for colocation and rackmounting
- How to reduce power consumption
- A word about mounting
- Stranded versus Solid Ethernet Cable
How to reduce power consumption
Modern CPUs use a disgusting amount of power. For us, power is the single most expensive thing we pay for, which is why we have a suggested donation schedule which is based on power usage.
To figure out how much power your CPU will drawn, you can consult these excellent pages:
users.erols.com/chare/elec.htm
www.techpowerup.com/cpudb/
A machine with dual P4 or Xeon CPUs can easily draw 2 Amps or more. If you are purchasing new equipment, please consider purchasing a Xeon LV (dual core), Opteron EE, or Opteron HE. These processors cost more than their power hungry counterparts, but they use one half to one forth the power. In the long run, you will save money.
If you don't need a lot of CPU power, than a VIA mini-itx is always a good low cost solution. Also, Pentium IIIs tend to be pretty low power.
Obviously, the CPU is not the only power draw. Disks are typically 8 to 15 Watts, and motherboards can vary a lot. In general, commodity hardware which was purchased off the shelf and then crammed into a rackmount case will consume a more power than the equivalent pre-built rackmount server.
Watts = Volts X Amp
Our voltage is 110, so a 100 Watt server uses a little less than one Amp. We are billed in Amps. Unfortunately, power supplies are far from perfect at converting AC power to DC power, so you will never get this theoretical efficiency. If you have an inefficient power supply (ie cheap), then the power factor will likely be crappy and you could end up using double the Amps than you might expect. If you have a really nice power supply, then your actual power draw will closer to the theoretical ideal. A power supply rated for more Watts does not in general draw more power, unless it sucks.
A word about mounting
Every piece of equipment in the colo needs to be mounted. This can be tricky, because sometimes a rail kit will cost more than an used rackmount server! Also, there are so many standards that there is really no standard at all.
SCCP uses 3/8 mounting brackets set to a depth of 29 inches. What does this mean? We use the large square holes for mounting, and the distance between the front mounting surface to the back mounting surface is 29 inches. Any scheme which you have for mounting must be able to work at that depth.
There are many standards for the mounting holes. We use 3/8 because it is the most flexible, and is becoming the most common. Using cage nuts or clip nuts, you can easily convert a 3/8 hole to a 10-32 threaded hole (it is even a little better because then you have some slight wiggle room).
Types of holes/screws:
- 3/8: These are the large square holes. They are common in Dell, Compaq, HP, and IBM equipment. The holes are unthreaded, and require a cage nut or clip nut to adapt to one of the threaded standards below. Sometimes this is called 9.54mm or 10mm, or just "big square hole".
- 10-32: Small threaded round holes. When Dell uses threaded holes, it typically uses 10-32. Most cage nuts and clip nuts are used to adapt from 3/8 to 10-32. Often used in audio racks.
- 12-24: Threaded round holes which are larger than 10-32. They are very common, particularly in 2 post telco racks and third party equipment, although we use them rarely.
- M6: threaded metric round holes. These are uncommon, but used by Compaq.
Images:
3/8 mount versus 10-32 mount
Cage Nut
Clip Nut
10-32 screw
12-24 screw
Stranded versus Solid Ethernet Cable
Some plugs will work with stranded or solid cable, but some will only work with one or the other. This diagram explains why:
Two point staggered for solid or stranded. The contact prongs straddle the conductor.
Piercing type for stranded. Jagged end pierces jacket and embeds into the strands of the conductor.
Tripoint type for solid or stranded. Long contact prongs spread apart to accept conductor.
