Build a low-power file server

One possibility is to build a server around a mini-ITX board with a VIA EPIA CPU which can be used to build fanless computers. The other possibility is to build it around a mini-ITX that uses an Intel ATOM CPU such as the Zotac ION.

In either case, you would probably want to put the hard drives outside the computer case, in their own box with its own temperature controlled fan. There are external cables that can be used to connect SATA drives, and even if the motherboard only has internal SATA connectors, you can get adaptors to allow you to connect external SATA. For the drive case, anything will do if you are willing to punch a hole in the case to run in the SATA cables.

I would like to build a file server for backups. The server needs to be available 24/7 in a mixed Windows/Linux network, but service should not exceed 1 hour per day. Thats why power consumption is my main priority.

What do you think is the best hardware to build it? What about software ? do you suggest a Linux distribution ?

In my experience, building a PC/File Server from scratch doesn't come close in terms of power efficiency to most consumer level NAS devices. With that being said, full-blown computers are obviously much more flexible/capable then consumer NASes, however home built anything will always consume more electricity. If you're lucky, you may be able to get consumption to within a few watts to consumer-ish hardware, but the time/effort/money may not be worth it.

I have NAS at home hooked up to a UPS, and just with the simple UPS monitor, it ranges from 45W-55W with just two drives. During off-peak times, it can get into the 30w-40w range. I have seen it as low as 25w but that's not common. That's not too shabby. Granted I have a 4-disk NAS, it's easier to operate, small and very energy efficient. Building is always fun but in the end can cost more, have more problems/maintenance, is physically much larger and consumes more electricity than a consumer-NAS counterpart.

Edit1: The server should take 1 to 4 terabyte drives, I'm not aiming at speed, redundancy is not a must, but will be appreciated if not very costly. My budget is kind of limited.

It's kind of odd that redundancy isn't a must considering it's a file server, but to each his/her own. If cost is the biggest issue and speed/redundancy are supplemental, 2-drive NAS devices should suffice.

Off the top of my head, I'd recommend the Netgear ReadyNAS Duo RND2000. It retails around $300+, but look on online retailers and you'll see they sell it for less. I think there's also a big rebate from Netgear on it as well these days but I'm not too sure. Note, Netgear sells most of their NASes with hard drives so prices seem to be inflated. Make sure to search for diskless versions.

Another NAS I'd recommend is the the QNAP TS-239 Pro. I own a TS-409 Pro but I've been very happy with QNAP as it's pretty rock solid. The software it comes with is fairly easy to use and works reliably. It's running Linux embedded so if you really want to dig into the internals, ssh access is available.

2 Disk NASes are fairly economical. The price range is fairly small from $100 to $300. 4 Disc NASes have a wider range of prices that will probably discourage you. They can range from $500-$900+. But it sounds like money is an issue so I'd go with 2-disk in your situation.

Edit2: If I can get a router or a wireless access point to do this job (using USB ports, and probably a modified firmware), then it would be a great idea. Any suggestion ?

I would stay away from this idea. While it may be the most economical/hacker-ish type solution, to me it smells like more trouble than it's worth. I've used DDWRT and Tomato and they're both fine ROMs for wireless routers/firewalls/vpns but file serving isn't something that I saw as a major priority with both projects. I could be wrong these days as it's been a while since I've used/played around with both, but if your files mean anything to you just get a cheap NAS device, hook it up to your LAN and call it a night.

I've setup a normal PC with external USB hard drive (for snapshots) and system on a USB key to perform backup.

The backup is scheduled each day in the evening and after it finishes the computer turns itself off. If we need backup, someone just sends the computer a WOL packet (using WOL the computer is turned on daily, just before the backup is scheduled).

Result:

• cheap (old PC, external USB drive, USB key),
• less power consuming (2-3h per day) and
• available anytime I need it (WOL)

PS.: OS Linux w/Samba and AD integration.

I recommend OpenFiler (http://openfiler.com/). It's a Linux-based NAS appliance, and it supports NFS, CIFS, WebDAV, RSYNC, FTP, and iSCSI. It can also be tied into Active Directory for authentication if necessary, or it can use itself as an LDAP server. I've been using it for a while, and I love it. It's easy to configure with the included management website.

OpenFiler also supports software RAID, so if you're looking to spend less on hardware, you can still have redundancy.

As for hardware, I would look for a mini-ITX system. That would be low power, and the BIOS probably has options for spinning down hard drives when unused. That would help cut the power usage significantly, especially if they can be spun down roughly 23 hours per day. There's also options within Linux to spin down drives when unused, such as setting the drive options using hdparm or installing software like noflushd.

Nobody seems to have suggested this but the choice of hard drives would also play a factor. In this case, the Western Digital Green drives are supposed to be made for low power. I use them in my file-server and they run very cool.

For a system platform, take a look at a HP ML110 or ML115. These are quite cheap (dirt cheap on ebay, often £100-200; retail prices start at about £300-400.), small (about the size of a mini-tower PC) and have space for 4 3.5" SATA drives internally. They also have a couple of exposed 5.25" bays that you could use for a tape backup unit or other removable media.

Recent models also have a PCI-e x8 slot if you want to install a hardware RAID controller.

If you buy one with a slower, low-power chip, power consumption will be relatively low. In particular, look at some of the low-power Opteron options for a ML115. If the system is mostly idle, it will draw relatively little power.

For a distro, there are various appropriate linux distributions such as Ubuntu Server or Fedora, plus some more tailored systems like OpenFiler. Recent versions of Samba will fake a domain controller if you need them to.

install linux on linksys nslu2 nas http://www.nslu2-linux.org/

I just built myself exactly this... the motherboard is a zotac IONITX-C-U, which is essentially just an Intel Atom CPU with the Nvidia chipset around it. I chose this because it's reasonably well supported bu Ubuntu, and because it has 3 SATA ports. My logic for the 3 SATA ports is as follows: I can build an infinitely extensible RAID 5 array. When you're close to full, you basically pull one of the drives to make room for the new 1TB one, then copy all the data over to it... then install two more new drives in the RAID5 array, copy the data from the first 1TB to the new array, then add that drive into the array. If you want to be even safer, you could use an external USB enclosure/adapter to do the copy so you're never left un-raided. In any case... I installed the ubuntu OS itself onto a simple 4GB USB flash drive -- no point in wasting a high speed SATA port for the OS given how little it's used. A reasonable performing USB drive is plenty fast for my purposes, and it consumes almost zero additional power.

The base system (motherboard + USB drive for the OS) clocks in at about 25W when it's being used... more like 20-22W when it just sits there. The total usage will obviously depend a lot on what kind of drives you choose for your bulk storage, but you can pretty safely assume something like 6-10W per drive when active... if you spin them down the incremental power consumption is pretty much zero.

so in general, I'm pretty sure that any of the mini-ITX boards will do what you want... ubuntu is a pretty friendly and well-supported OS, and it also gives you the flexibility to mess around with other things that aren't strictly file-server related. (This may be a good thing or a bad thing depending on how isolated you want your server to be!)

This has got virtualisation written all over it - have you considered that option?

One thing I'd be interested in trying is the Beagle Board. It costs ~$150 (US, presumably), and (according to wikipedia) only uses 2 Watts of power. It sounds like a few Linux distros will run on it.

I'd have to look into it some more to know for sure; the basic board will use a flash card; however, I think you could use external USB hard drives (in which case you'd have to factor in the power they use, and, if they are powered by the USB port, you'd probably need a powered USB hub.) I'm just guessing, though, as I haven't looked into it for a while.