4 ms·

> plug in their old hard drives I honestly have no idea how inefficient 'old' spinning disk hard drives might be, but I wouldn't be surprised if an older drive

> plug in their old hard drives I honestly have no idea how inefficient 'old' spinning disk hard drives might be, but I wouldn't be surprised if an older drive consumes more electricity than a modern, power-sipping ARM-based RPi. Maybe GP took that into consideration?

Crito 12y ago
Compared to the power requirements of an RPi, the power for several spindle drives would be pretty significant.. except you have to figure they won't be spun up most of the time.
lunixbochs 12y ago
11W is about the highest active draw I've seen on a drive datasheet. As far as I know, the power usage hasn't really changed in a while because it's mostly attributed to the 5400-7200RPM motor. The control board is very specialized and draws effectively no power in comparison. The Raspberry Pi can run on a 5V / 500mAh bus, which is a 2.5W max load. This gives us a theoretical 13.5W max constant draw (which is likely much higher than reality, as we're talking about rated power instead of measured). 13.5W * 24h * 365 = 118260Wh = 118.260kWh max in a year At 16 cents per kWh (a lowish power tier for PG&E in Silicon Valley), this comes out to $18.92 a year. These numbers assume a 100% efficient power supply running the unit, but are also talking about theoretical maximum power draw and not observed power. This is also a fraction of the average power draw of any of these you might use: electric oven/range, microwave, fridge, incandescent lights, electric dryer, electric water heater. As far as observed power: I've seen a fairly efficient Intel motherboard (CPU TDP of 17W) with 8 modern spinning disks drawing around 75W (measured at the wall using a Kill-A-Watt with all drives active) so I'd guess the real-world number is <8W per active drive.
- e12e 12y ago
  There's really no reason for the hd to be powered most of the time, for this use-case. Download the backup (couple of days to a week for 500gb?) -- spin down the drive. Only needs to spin up if anyone wants to read the data. Now if we move away from the idea of "backup" to just: lets make a set of torrents, and try for many copies of each chunk/DHT -- then that's a different story. It'd be interesting to see how efficient one could make such a "massively distributed content dispersion network". Imagine: suddenly the www is distributed, not centralized again!
  - lunixbochs 12y ago
    "Active idle" on a drive is still rated at around 5W. Maybe they don't spin down completely in the idle state? BackBlaze says it's better for the longevity of a drive to leave it running than to power it on and off regularly.
    - e12e 12y ago
      > it's better for the longevity of a drive to leave it running than to power it on and off regularly. Sure, for the general use-case. But if this was "just" for backup, powering up would probably be quite rare. If it was for content distribution (eg: torrent) with some expected semi-frequent access, leaving the drive on would probably be best. With an USB-disk (or a disk in a USB enclosure) it should be possible to power it down completely. The main problem then would be powering it up again -- I'm not sure if there's an API/interface for powering up an USB device that has been powered down, other than plugging it out and in again?

Crito 12y ago

Compared to the power requirements of an RPi, the power for several spindle drives would be pretty significant.. except you have to figure they won't be spun up most of the time.

lunixbochs 12y ago

11W is about the highest active draw I've seen on a drive datasheet. As far as I know, the power usage hasn't really changed in a while because it's mostly attributed to the 5400-7200RPM motor. The control board is very specialized and draws effectively no power in comparison. The Raspberry Pi can run on a 5V / 500mAh bus, which is a 2.5W max load. This gives us a theoretical 13.5W max constant draw (which is likely much higher than reality, as we're talking about rated power instead of measured). 13.5W * 24h * 365 = 118260Wh = 118.260kWh max in a year At 16 cents per kWh (a lowish power tier for PG&E in Silicon Valley), this comes out to $18.92 a year. These numbers assume a 100% efficient power supply running the unit, but are also talking about theoretical maximum power draw and not observed power. This is also a fraction of the average power draw of any of these you might use: electric oven/range, microwave, fridge, incandescent lights, electric dryer, electric water heater. As far as observed power: I've seen a fairly efficient Intel motherboard (CPU TDP of 17W) with 8 modern spinning disks drawing around 75W (measured at the wall using a Kill-A-Watt with all drives active) so I'd guess the real-world number is <8W per active drive.

e12e 12y ago
There's really no reason for the hd to be powered most of the time, for this use-case. Download the backup (couple of days to a week for 500gb?) -- spin down the drive. Only needs to spin up if anyone wants to read the data. Now if we move away from the idea of "backup" to just: lets make a set of torrents, and try for many copies of each chunk/DHT -- then that's a different story. It'd be interesting to see how efficient one could make such a "massively distributed content dispersion network". Imagine: suddenly the www is distributed, not centralized again!
- lunixbochs 12y ago
  "Active idle" on a drive is still rated at around 5W. Maybe they don't spin down completely in the idle state? BackBlaze says it's better for the longevity of a drive to leave it running than to power it on and off regularly.
  - e12e 12y ago
    > it's better for the longevity of a drive to leave it running than to power it on and off regularly. Sure, for the general use-case. But if this was "just" for backup, powering up would probably be quite rare. If it was for content distribution (eg: torrent) with some expected semi-frequent access, leaving the drive on would probably be best. With an USB-disk (or a disk in a USB enclosure) it should be possible to power it down completely. The main problem then would be powering it up again -- I'm not sure if there's an API/interface for powering up an USB device that has been powered down, other than plugging it out and in again?