External HDD power question

Support for your TonidoPlug
andrewcorser
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External HDD power question

Postby andrewcorser » Sun Jul 17, 2011 4:36 am

I would like to be able to run my Tonidoplug as a "green server" with an external HDD. There are a whole load of question that come up. The particular problem that I want to address in this post is that the external HDD I have (a LaCie 1 Tb drive) has its own power source, and it is running all the time. I haven't checked up how much power the HDD is using when it isn't being accessed, but it is "humming" as though it is spinning the whole time it is on - presumably using rather more power than it needs to.

So:

Are there HDD's that use very little power when not being accessed?
Or, if I use an HDD that is usb-powered, will that not use any power until accessed?
I read the post about such drives being connected via a USB hub - do these use power, or are they "passive"?
I realise that any system that has to wait for the HDD to fire up will take longer than one that is on all the time - if the system is going to fire up the HDD each time it tries to access it, will this either be unusably slow, or will it damage the HDD?
Or is there a way that the Tonidoplug can fire up an external HDD for a period, say 15 minutes, when required?

I realise there is a lot here, but for the Tonidoplug to be the green server the adverts suggest it can be, it seems to me that the power consumption of the necessary external HDD is an important issue.

Many thanks!

Andrew Corser
Cornwall, UK
"Working towards decentralised cloud computing under personal control"

neato
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Re: External HDD power question

Postby neato » Mon Jul 18, 2011 9:55 pm

If you have your tonido profile installed on the external hard drive, then tonido will not let the hard drive spin down as it is constantly querying for changes. You cannot get around this unfortunately. But it allows the Tonido software to be responsive.

If your tonido profile is installed on the plug, then I believe whether the hard drive spins down or not is specific to the particular hard drive (it may be controlled by the linux OS too, I'm not completely sure). It seems weird to me that today there would be an external hard drive that would not be programmed to spin down after a certain length of inactivity, but there may still be drives being designed this way. In any case, it is something that you can research about for a particular drive before you purchase it.

The amount of power that is consumer by a hard drive is also drive specific and should be able to be determined with a bit of googling and/or contacting the manufacturer.

A hard drive will always consume some amount of power when turned on. If idling, it consumes less then when spinning. Regardless, some amount of power will always be consumed through the usb-hub when turned on.

Allowing a hard drive to idle will not damage it. In fact I imagine it may improve it's life span. It is also more energy efficient as you allude to. However, the spin-up time will be noticeable when trying to access it. But once it has spun up, it will behave quickly for the amount of time it stays spun up.

dongadoy
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Re: External HDD power question

Postby dongadoy » Tue Jul 19, 2011 8:27 am

There have been lots of posts regarding hard drives going to sleep. Tonidoplug does not work with most (or maybe all) of those green hard drives. Their ability to sleep must be turned off; otherwise Tonido will disable apps that use the hard drive. I don't know whether it is a Tonido problem or a Linux problem.

I read somewhere that today's hard drives are built to spin down when not in use, and spin up quickly when needed. So, keeping the hard drive spinning constantly will reduce its lifespan. It's very hard to know if that reduction is significant for an individual.

As the neato wrote, hard drive power requirements are vary significantly between models and brands. I know there's a rating for how much power the USB port can safely deliver; but I can't find it at the moment. I successfully used an USB-powered 2.5" laptop hard drive for a short time when I first got my Tonidoplug.

I have opted to use a flash drive. My Tonidoplug will sit idle most of the time and keeping a hard drive spinning constantly seemed like a bad idea to me. And it uses much less power (no spin-up) so it can be plugged directly into the Tonidoplug. The 64GB flash drive is fine for my MP3s and photos. But it will not work for anyone with videos or other huge file types.


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