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I currently run a number of home servers for various purposes (email, web, IM, NFS, PBX, calendar, MythTV, music & DNS hosting). These are running on five different systems around the house. At times, this strikes me as excessive!
Ever since VMWare launched their free server offering, I have been wanting to consolidate the number of systems, however the hindrance was always the amount of RAM that I would need to purchase to make the host run properly.
Recently, I have been thinking about the cost of electricity vs the cost of the additional RAM and I started to do some calculations. We get our electricity from Energy Australia on their SmartMeter tariff which varies the cost of the power during the day:
- Mon - Fri: 9 hours off-peak, 9 hours shoulder, 6 hours peak
- Weekend: 9 hours off-peak, 25 hours shoulder
The rates for these three tariffs are currently (per kWh):
- 8.14c off-peak
- 14.08c shoulder
- 35.64c peak (pricey)
A quick calculation works out the weekly hours as 63 off-peak, 75 shoulder and 30 peak which costs $26.38 per kW.
One of my servers (mail & NFS) is a Dell SC420 which uses about 160W when idle according to this report.
This means that one of my systems costs me $220 a year to run. That is a lot more than I thought!
I think that I can virtualise my Dell GX150 (Asterisk VOIP PBX server) and HP/Compaq EVO D510 SFF (web & IM) without too much drama. These boxes are smaller than the SC420 and the environmental reports for these are not available, but I reckon that there is a saving of $300 a year to be made by switching them off.
I have just purchased 2Gb RAM for the SC420 so that I can install and run VirtualBox without any performance problems. This will increase the current memory footprint five-fold and will easily swallow the other two servers memory requirements. Total cost for the RAM: $60.
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