I have been looking into using HDDs for long term storage instead of DVDs. Now that I am happy with reliability issues and HDD prices have fallen to almost match DVDs in price per megabyte, I am interested in low power solutions for multiple HDDs.

The idea is to have an external box with two or more HDDs in it. The box is connected to the PC somehow.

Looking at standard drive enclosures, the biggest issue is lack of adequate power control. Most have power switches on the back of the unit, but need to be properly dismounted from Windows first. USB enclosures do not support drive spin-down. Also, having one PSU per HDD is not very efficient, and leads to a mess of power cables.

So, get a small case and fill it with HDDs and controllers. Sadly, all USB controllers only seem to support a single drive. Why not a master and slave? Anyway, at least this way you could have one PSU and a switch for each drive. Perhaps use eSATA and use spin-down.

A better option would be NAS, but the issue is power usage. When idle (most of the time), NAS still draws power for the computer part. No-one has yet invented an ultra-low power NAS board that doesn't cost a silly amount. At least, not one that doesn't suffer from the same problem as USB enclosures: the only support a single drive.

Bus-powered Firewire looked like an interesting option, but it seems that it often tends to trash the Firewire port it is connected to.

So, my current plan is to get something like an old Sun disk array box and mod it. The Sun boxes are basically designed to take 8 HDDs and have a PSU with SCSI backplane. I will strip out the SCSI stuff and mod the PSU just to power the drives. Add some switches to the front for individual drives. Finally, install either eSATA or USB adaptors for the drives. eSATA is probably best, but USB does have the advantage of being able to build a hub into the enclosure and thus bring the number of cables down.

Any comments?

What about a a setup that goes into standby with wake-on-LAN functionality? Alternatively, is the consumption of the computer part really that big a deal? Assuming a Via C3 solution or the like, how many Watts are you really saving, 20? Even if the thing is idle 8,000 hrs a year, how much does 160 kWhrs cost, $20, $30 (don't know about UK, but in US few pay > $0.15/kWhr)? While the idea of saving electricity through better efficiency is noble, it may not be worth the trouble.

I'd have to agree with Jesse. The added hassle of adding switches and running several different controller cards would more than offset the power consumed by a low power full-fledged computer which could do everything you need (switching drives, sharing media etc)and imo be a cleaner and more functional solution.

Interesting points guys. I am tending to agree with you, and one nice thing about always-on NAS is that you can use it as a media server and perhaps even overnight BT downloader.

The question now is, what computer? I want to keep costs down so Via stuff is out of the question, and the case needs to have plenty of room for drives as well as hopefully being small and reasonably well cooled. That is why the Sun boxes are attractive. Shame SCSI is not an option as of course it has SCSI built in.

I have been looking at embedded boards, but most don't have much in the way of IO. Even Via boards are usually quite minimal.

One really nice solution I saw in Japan is a tower that can take up to 8 HDDs, and gives you a single USB connector. It was quite expensive though. Had power saving features though.

One major advantage of SATA is that you can use power management on your PC, and monitor SMART as well. Even if you just left it always on and relied on power management...

Someone needs to make cheap NAS boards with 4 SATA ports and a small size.

I don't know what's available there, but here in the U.S.A., NewEgg has a cheap Via CPU motherboard for $60 which is ideal for a low budget server. It's mATX, and a LOT less expensive than VIa's mini-ITX motherboards.

PC CHIPS V21G V1.0C VIA C7 VIA CN700

Maybe you can find a similar deal somewhere there. Just make sure to look for mATX or flex-ATX motherboards rather than the expensive mini-ITX motherboards.

(The mini-ITX motherboards tend to not have enough hard drive ports anyway. The example I gave above has two IDE ports and two SATA ports; enough for six hard drives.

IsaccKuo: sadly that board does not seem to be available in Europe. Still, the flex-ATX idea might be a good one. I was wondering if I could somehow use a laptop board for ultra-low power and cheapness, but a lack of IDE/SATA/PCI is the problem.

I'm tempted to buy a NAS enclosure and try to hack it. At the very least, I think two drives in master/slave should work. Most seem to have upgradeable firmware, with hints in the file names that it should be possible to run multiple drives.

One other thought I just had. Regarding power, might disconnecting from the mains when not in use be a good idea?

There are a lot of power spikes where I live. Old houses, old wiring, crap electicity company. I use a surge protector, but I like the fact that my backup USB HDD is totally disconnected from everything when not in use.

That might be possible with USB. Sadly not easily with eSATA, but at least the power supply could be on a large isolation switch.

Just one more update. The cheapest way seems to be USB adaptors with a custom case.

The USB adaptors can be bought for as little as £2.50 without a PSU. A modded Sun case should provide the rest. Easy power the whole the on or off, and a USB hub reduces the number of cables to 2.

C'mon guys, let's not give up so easily! This is the green computing board, not the convenience computing board

Mind you, my current setup is an NAS that spins down after 10 min, but I'd love to figure out a way to cut its energy consumption further. So I want to hear some imaginative ideas of what more can be done. Put a timer on it so it (and other electronics) are only on for part of the day? Turn it on/off manually?

Maybe the best solution is a NAS, but let's not give up yet!

I think we've pretty much agreed that a complete, low power computer system will be your best bet. I'm not sure about Europe but here in the states it's not uncommon to find a cpu+mobo combo that will run fanless and dissipate under 20W at full load for under $100. The advantages of having a complete system rather than just an external HD box are abundant and, once again, the (extra?) power consumed will quickly be offset by the lack of hassle you would encounter trying to "hack" another NAS or gutting an old sun case. IDE or SATA controller cards are cheap and if you know which type of drives you'll be running (PATA/SATA) you can buy a board that will be better setup for that interface. 2xPATA onboard + 2xPATA on one controller card could give you the 8 devices you were looking for. Likewise with SATA.

The greenest journey is the one never taken.

I'm not sure I'd give up on Via that easily, though. You don't need C7 for NAS, a C3 would be fine. There are so many < $100 C3 boards listed on Newegg that I can't believe none of them are available in the UK. If there really are none, just get a micro-ATX board bundled with a low-end AMD Sempron for < $100. In choosing your combo, employ some search-fu and find one where the board supports undervolting the CPU. An undervolted Sempron is basically an AMD Geode without having to find the less common processor. The only reason I like the C3 better for this application is that you don't have to spend a lot of time searching for combos with an undervolt-capable board.

What about my idea of employing wake-on-LAN for PC-based NAS? That way you could set the NAS to go to sleep after some period of inactivity and when you need it again just run some little program that will send out the right packets to wake it up.

Thanks for the comments guys.

I like the idea of a NAS with wake-on-lan. I should point out that as well as saving the planet I am also interested in saving my wallet. It's a real shame all the Via vendors in Europe are such rip-off merchants. The cheapest C3 based board I could find was £97, and that was refurbished. Even on eBay the prices get silly, but I will keep looking.

Size is also an issue. I like the Via boards because they are small, but again Flex-ATX boards of any kind tend to be stupidly priced here. I have been looking into Thin Client boards and Single Board Computers. The Sempron idea is a good one, but would mean ending up with a full size case. I like the Sun boxes because they are cheap and small and designed for taking HDDs.

One other option is a laptop board. Single voltage power supply requirement, and SATA can be added via a PCMCIA card. Very low power of course.

NAS has another advantage of pure convenience: the host computer can run additional tasks like disk surface scans, SMART monitoring and disk migration by itself. As I mentioned, it could also be useful for slow BT downloads (I watch a lot of Japanese TV, sometimes it can be slow).

In some ways it might just be easier to get an off-the-shelf NAS solution. External NAS enclosures for single drives can be had for £25.

Why do towers with a PSU, HDD slots and USB->IDE interface cost £150? You could easily buy a standard computer case and set of USB adaptors for less, or a mobo+CPU+RAM for NAS.

The price premium is because it is a real pain in the ass to find a "normal" case that has a good layout for this. Most small cases are designed to hold, at most, 3 HD. PC cases designed to hold a bunch of HD are huge. If all you need are 1 or 2 HD, there are almost no cases that are as small as they should be for this task.

That's what it boils down to, isn't it? I have been looking at tape drive enclosures. Typically they are full height 3.5" affairs with a built in PSU. Might be moddable.

One other issue - hard drive spin down with NAS.

I have been looking into this, but there seems to be little hard info. Say the box has 512MB RAM and runs Windows 2000. That would give it at least 450MB to use just for disk cache. But how useful will this be for stopping the disks spinning up?

In theory, all previously opened directories should be cached and not require the drive to spin up. Testing with a spare machine and Windows XP though, this does not seem to be the case. I have tried the disabling the usual suspects, like LastUpdateTime and any unneeded services.

Maybe Linux is better? Then again, I have always found power management in Linux to be flaky.

The OS will never spin down the disks by default, this is something you need to set explicitly. For Windows, you need to go into power management and tell it to turn off the HD after some amount of inactivity. Linux and other OS have similar settings, but how to access them vary. Don't set the inactivity period too short, as constantly stopping and restarting the drive will reduce its life. An optimal inactive time is likely 1-2 hrs.

Now, if you use wake-on-LAN, this whole issue goes away. Instead of justing shutting down the disk after an hour or two of inactivity, the whole PC will go to sleep. Having the PC in sleep mode, even with a Via C3 setup, is going to double your power savings over just shutting down an HD (maybe even 2 HD). Again, for Windows, this is something you set through power management (+ you need to enable wake-on-LAN in BIOS).

What I mean is, Windows spins the drives down as per power management, but spins them back up again the moment any other machine accesses them in almost any way.

For example, if you browse the networked computer, or map the drives as local drives and use some bit of software that checks available free space, it spins the drives up again. Really, that kind of stuff should rely purely on the memory cache.

Low power and low cost Home Server/NAS/backup or storage solutions is something that I have been putting alot of time into lately. More specifically, solutions with 4 or more HDD's for storage.

My Theory: In the next 2-4 years the need for need for 'personal storage' will rise dramatically as adoption of storage intensive sources and habits become cheaper, mainstream, and practical.

A list of storage intensive sources or habits:
- High mega pixel cameras
- HD video camcorders
- Large Multimedia Libraries (itunes, etc)
- Backup of purchased DVD's
- HTPC's
- HD video/audio editing
- backups of 1 or more personal computers
- backups of purchased software (OS, applications, games)
- P2P activity (movies, music, PRON, TV episodes)
- Preference for redundant capabilities such as flavors of Raid mirroring or Raid 5


Here are some conclusions that I came up with:

1. Mini-ITX offers no advantages

Mini-ITX is a great form-factor, and while it consumes less power compared to high end desktops, when comparing it to frugal and more capable AMD or mobile CPU solutions it becomes unattractive very quickly. An EPIA 800mhz C3 board uses about 35W which is 5W less than a 1.8ghz Corel Solo on a MSI 945GT speedster (which has 4xsata on board negating the need to purchase additional cards to increase mini-itx storage capabilities).

2. DVD's are acceptable for backups, but not for storage

With bulk cheap dvd's you can get the cost per GB down to about 6 cents, which is far cheaper than even the best ratio HDDs can offer (about 25 cents per GB). The problem is it will take about 25 hours to burn 500 GB of data using a backup program (which generally makes it difficult to get acess to individual files quickly). HDD's can used for automated archiving and storage without the need to spend time contantly selecting files and changing media. Additionally, 500GB of DVD's is a lot of plastic that will eventually wind up in a landfill.

3. External HDD solutions cause more problems than they solve

While external HDDs offer alot of convenience, they lose their advantage if you have them always connected to your computer, especially if you want to make files and storage available to others. External HDD's are a great supplement to Home server/NAS type solutions, not an alternative.

Getting the most GB/$1 in a home server/NAS

I would say $0.50 is the threashold for a home server/NAS solution. Consider what components you have, and what you will need to purchase, and if you can do it for less than 50 cents per GB (1000bytes not 1024bytes, just makes the math easier=) then it's a viable option.

I'm trying to figure out ways to reduce the cost per GB based on 1TB of storage. There's a couple of ways to do this:

#1 Recycle any old components that make sense
#2 Balance Price/Performance/Power Consumption
#3 Fewer components is better
#4 Build your own case or recycle instead of buying a new one
#5 If you need to buy a CPU, try to find a used one

Ah, well that is just the nature of things. I know of no modern OS that acts as a HD cache. Indeed, the opposite is generally true, with the OS paging things from memory to HD to free up RAM for a rainy day. Things are set up this way because HD are a lot cheaper per megabyte than RAM and power efficiency has only recently become a hot topic. What you are looking for is either Intel's forthcoming Robson technology or the also forthcoming Hybrid Hard Drives. Robson puts a big hunk of flash memory on the motherboard that integrates with the HD controller to let the HD sleep more and also to let the machine boot and come out of standby faster. H-HD is basically the same thing, but the flash is built right into the HD package. H-HD are intended for laptops and will likely only be available as 2.5" and smaller form factor. Both Hybrid HD and Robson should be available any day now . . . The best option that is available right now is to just use 2.5" drives as they use a lot (like 5-7 W) less power when idle than 3.5" drives (and less power when active too). The downside, of course, is the higher cost per megabyte. Again, this may be a case where the cost of electricity is less than the cost of more efficient components.

Really? That would mean the board itself is using 30W! I don't disbelieve you, but that doesn't sound right. Where did this information come from? Could it be that the IGP on the EPIA is a huge energy hog?

I used a Kill-a-watt meter, which isn't the most accurate, but I made the comparison using the same ATX power supply (instead of using a DC-DC adapter board + power brick for the Mini-ITX)

Using a ATX PS is not the best choice for Mini-ITX, especially because at low power levels they tend to be far less efficient, but they are considerably cheaper and more capable than the DC + power brick

A mini-ITX C3 800 mhz with 4 HDD's and a gig of ram will probably be in the same ballpark as a AMD manila Sempron with 4HDD (assuming they are at idle) using an ATX PS.

4 HDD's on a DC-DC + power brick is a tough thing to do and would cost $60 more at least for the components vs a ATX PS

Well, if you are up to 4 HD you are way past needing a mini-ITX MB (unless you are trying to mod some other kind of box into a case that has no wasted space). If you don't need mini-ITX then undervolting a cheap AMD CPU on a µATX MB seems like a good way to go. I don't know if your extra $60 for DC-DC + brick is fair, though. We're trying for silence right? A Seasonic S12-330 is $60 vs $80 for PicoPSU-120 + 80W brick. As for running 4 HD off a brick, you're right it may be cutting things too close considering must fanless bricks are only <= 80W and 3.5" drives need about 10W each.

In my experience an EPIA 800mhz C3 system uses 10-15w less than a Sempron 3000 w/CnQ turned on and both systems idling using the same PSU (Seasonic Super Tornado 300w, not that efficient below 50w, either, but it was the best I knew of when I bought it). The Epia barebone system was around 25-30w with the Sempron around 40-45w at idle measured with a Kill-a-Watt. Single 7200rpm hard drive and both using integrated graphics.

Don't forget porn!



This is very true. You could probably bring things down even more with the use of a DC-DC PSU and careful choice of minimalist board, combined with turning off everything you don't need (like USB, serial/parallel ports etc). A board without IGP, or with IGP which can be disabled would be good too. Once the OS is installed there is no need for any graphics at all... although, I wonder how many boards would boot with no graphics card?



Indeed... they are a pain the ass to organise and take too long to burn. Plus, unless you buy good ones they don't last. By "good ones", I mean Taiyo Yuden which are generally about £40 per 100. 9.3p per gigabyte, probably more as it's hard to fill DVDs exactly. HDDs are around 15p/gig but a lot easier to use. Reliability is still an issue.



Perhaps... if you watch media on your PC, or streaming from your PC, there is no reason why you can't just use an external drive. You can even share external drives for access from media centres.

Also, one major advantage of external HDDs is immunity to electrical damage. Assuming you totally disconnect the drives when not in use, power spikes won't be able to hurt the drive.



This is one major goal for me. Sure, HDDs are cheap, but why not recycle old 40/80GB HDDs as well? If they are still perfectly operational, there is no reason not to use them. Putting them in the main PC does not make sense - more heat and space taken up. But having them external for archive use or on a NAS tucked away somewhere would be OK.

Indeed, but I found a way to sort it out. You need to change the Windows VM management model to use a large cache for files. How you do this depends on the version of Windows you have, but the LargeSystemCache registry entry is the key. With that an things like LastAccessUpdate turned off (or even better, use the Windows EXT2 driver, although that has some serious limitations) and a really minimal system, it does mostly work.

One more comment. The biggest hurdle in this seems to be finding a suitable case. Most external cases are only for one drive, or are very expensive for no apparent reason. Most computer cases that have more than two 3.5" bays are quite large or have poor cooling, when really you want a small but well cooled case for NAS.

You can basically rule MiniITX out on price for the most part. It's not just the boards, it's the cases and PSUs etc. Also, as has been pointed out DC-DC PSUs often don't have enough power for multiple HDDs anyway.

One possible option might be Small Form Factor (SFF) cases. Many companies make them but they are not that common in Europe. Most Japanese computers are SFF. Basically an extra small uATX case, usually half width and designed for SFF half size PCI cards. HDD mounting options vary a lot, but some can mount at least three or more if you don't use the optical drive bay. Cooling can be a bit naff, but if HDDs are set to spin down when not in use chances are not more than one will be on most of the time anyway.

I have a Fujitsu Futro SFF PC I use as a router. 1.3GHz PIII, swapped for a 650MHz PIII which runs fanless. The PSU has a fan, but it is temperature controlled and it never comes on. I use it as a router running from compact flash.

The ideal would be a case similar to this: http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... &rd=1&rd=1

Loads of room for HDDs, and a built in PSU, and a "wind tunnel" set-up for cooling. I have often wondering about building something like this. Even with mechano or something...

You would need a very small mobo if you wanted NAS though. You can buy NAS mobos, but they are hard to come buy and expensive. That's why I though of getting one and using it with USB/eSATA. An industrial Single Board Computer (SBC) might fit, but they tend to lack much in the way of I/O. Some have PCI risers which may be a possibility.

whats wrong with just buying a 500gb harddrive, plugging it into your computer once to fill it up, and then putting it in a drawer?

It's like a huge 500gigabyte DVD, and it's rewritable. and power draw = 0.

that solution work fine, but is the 500GB drive a full backup like a mirror of a 500GB drive you have internally? If not and that drive decides to die, you can potentially lose everything that was on the drive.

also if you want to share the drive contents with others (either locally or over the internet) you'll have to leave it on - what if you want to add storage...get another external......and then another....etc... and all those power bricks start taking up space

externals are fine for "cold storage" or backups for of existing data on you computer, but they are not what I would call an accessible storage solution
especially when you are talking 1TB and above.

Since we are talking about green computing, 2 x 750GB HDD are the best solution in my opinion! Reusing 40G or 80G HDD's won't get us any were, because they will use just as much power as the 750 G. It is expensive but from a power consumption point of view is the best GB/W ratio . Hell, I'm still using a 80 G HDD and save stuff on DVD's and I'm talking about 1.5TB of storage!

A NAS or small file server makes sense (from my point of view and considering we all have 750GB HDD's ) only if there are more users accessing it! For example if you have more computers in your home...or even share the server with your neighbor! If you are the only person using it it would make sense if you had a notebook instead of a desktop, since 1.5TB of storage seams more then enough for me !

Also, an alternative to wake-on-lan is Stand-By mode! I used to own a P4 Compaq, and when it entered in stand-by it shut down everything, including the PSU. When I changed the motherboard and entered in stand by the PSU was still on! I believe that it had something to do with the Compaq motherboard!