A Low Power Bittorrent ServerFirst, select a processor and system. There are many options. The lowest power processors x86 processors are made by Via. I decided the Via processors are generally underpowered and somewhat expensive. The next lowest power processors are notebook processors. They are generally more expensive and motherboards for them are limited and expensive. If you had an old notebook lying around, that would make a fine bittorrent server (possibly needing an external disk). The Pentium III 733 is a reasonably fast, reasonably low power processor. One limitation is there is almost no power saving when the cpu is idle. Virtually all processors made the last 3 years draw less power when idle. In the last two years processors drop their frequency and voltage when load goes down. This was first available with notebook processors, but migrated to the desktop, as desktop processors use more power than notebook processors. If I couldn't locate an old system, I would likely use a low power desktop processor, as they are cheap and readily available. Many motherboards allow the processor voltage to be lowered, or there are software programs such as RM Clock that will allow setting the processor voltage as a function of load. I have used RM Clock to drop my notebook voltages on Turion as well as Core 2 Duo systems. Dropping the voltage n percent will reduce power by approximately n^2 percent. I have dropped my notebook voltage by 20%, which means a 36% reduction in power. |
Rather than buy a new computer, I decided to use an existing (free) IBM desktop Pentium III system. The cost is unbeatable, the form factor desirable, and the CPU is relatively low power. I read the IBM manuals and found this particular model doesn't accept ECC memory, though other IBM desktop models do. This isn't ideal, so I am now in the market for another low power system that takes ECC and is cheap. It came with a 20gb hard drive which was dedicated to the OS. A 200gb hard drive was added for storing the files. This machine was old enough that the BIOS didn't recognize the hard drive was over 137gb (new BIOS's know about big hard drives) but it wasn't a problem as the loaded OS didn't use the BIOS to access the big hard drive. The existing graphics card was adequate, as was the 10/100 Ethernet card. I eventually added a low power AGP video card with 32 mbytes of RAM, since I use a KVM switch, and I have a high resolution screen.
For software, a recent version of Linux was selected. In addition to being free, I think that Linux is much more secure than any version of Windows. It also can be configured to not require lots of resources, which is important with older hardware. ssh was enabled to transfer files to and from the server. A firewall was installed, and it allows ssh and the bittorrent protocol in. TCP wrappers was used to limit tcp access. The machine has never crashed.
Power consumption:
I ordered an adapter so I can use a notebook hard drive rather than a 3.5 inch hard drive for the OS. (If you do this, get adapter rails to mount a 2.5 inch drive in a 3.5 inch bay. My solution was a kludge.) Power consumption with the notebook drive:
I may also buy a seasonix SFX form factor 80+ power which should also save a few watts. It won't be very cost effective however.
After about a year the 2.5 inch notebook hard drive became unreliable, which produced a variety of amusing symptoms such as the computer hanging. A friend pointed out that most notebook drives aren't designed for 24x7 operation, which I was subjecting mine to. (The drive itself had come from a 5 year old notebook computer.) I disconnected the drive and reformatted the 200gb hard drive to have the OS as well as the bittorrent storage area. I have re-thought my desire for running a 2.5 inch drive, unless it is rated for 24x7 operation. If I was building a bittorrent server from scratch I might consider one of the 'green' 3.5 inch drives, as they are lower power than most conventional drives.
I wanted a lower power bittorrent server. I considered the Intel Atom, but with the current chipset, the power consumption was almost as high as my Pentium III 733 system. With the Intel D945GCLF m-ITX motherboard which has a single core Atom and a notebook hard drive, it idles at 27 watts. With the Zotac IONITX-A, which has the ION chipset and a dual-core Atom and a notebook hard drive, it idles at 22 watts. I considered an ARM chip based system. The best one I found was the SheevePlug development system. It features gigabit ethernet, USB2, draws about 5 watts, and costs $100. The downside was very limited Java support (Java is what Azureus and some other bittorrent programs are written it.) Also it didn't have a keyboard, mouse, or video connector. I could work around the KVM problem by using vnc or ssh, but it would be a bit of a hassle. I decided to stick with an x86 based processor.
I got a notebook from a friend with a Pentium III 1000. I found out that it used a desktop chip when I opened it up to change the BIOS battery. Also, the external video didn't work under windows or linux, which was a bit of a problem. It did have a firewire port, which was a nice touch. I ended up using an old Compaq Evo N-600 notebook I bought about 6 years ago. It has a Pentium III 1.2ghz mobile chip. It didn't have firewire or usb2, but the external video worked. The notebook has a single PS/2 port which supportes a keyboard and mouse PS/2 splitter, enabling me to use it with my KVM switch. It had come with 256mb of ram, but I had added 512mb of ram, and it supports a maximum of 1gb. I wish it supported ECC memory, but I have never seen a x86 based notebook support ECC memory. The hard drive was not big enough for storing my bittorrent files, but it was plenty big for the operating system. I added a PCMCIA card which supports Firewire and USB2. I bought an external 320gb 2.5 inch drive, for storing the bittorrent files. It came with a 3 year warranty, which is a good thing, as I will be using it 24x7, and it runs pretty hot. When the screen is on, it draws 23-24 watts AC. After about 10 minutes, the screensaver starts and it draws 17 watts AC. That is about half the power of my previous bittorrent server. I run the notebook with the screen folded open completely. This way, I can access the power switch, and the notebook runs cooler, since much of the heatsink is under the keyboard. The fan rarely comes on, making it virtually silent (except for the 2 hard drives).
If you have comments or suggestions, Email me at turbo-www@weasel.com
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