[kwlug-disc] How much CPU to keep a disk fed? [Was: Re: Which vendor for Raspberry Pi kits?]

unsolicited unsolicited at swiz.ca
Tue Dec 10 05:07:40 EST 2013


Good info, but meant CPU (horse)power, not electrical power. (-:

- was expecting GHz not mA. (-:

On that electrical power ... less need for usb hub power if external usb 
(enclosures) are powered?

On 13-12-10 02:25 AM, Bob Jonkman wrote:
> unsolicited wrote:
>> Just how much CPU power does it take to keep a (USB? eSata?) disk fed,
>> anyways?
>
> A USB socket is required to provide 500mA. If you plug a USB extender
> into computer, that computer's USB port can only supply 500mA for all
> the ports on the extender (and the extender itself). That's fine for a
> thumbdrive or two, but if you're trying to use an external, spinning
> disk you'll need an extender with a power supply.  I've got a couple of
> 5+ year old external USB drives for which the cables have double USB A
> connector, one for data+500 mA and the other for another 500 mA.
>
> Don't know about eSATA, but on my computer the USB 3.0 port and the
> eSATA port share one physical connector (ie. I can use either USB or
> eSATA, but not both at the same time). So I suspect eSATA has the same
> 500 mA limit. OTOH, my external eSATA drive has its own power supply.
>
> I was reading earlier this week that the new USB spec will supply up to
> 5A at 12V, which seems ridiculously high.
> http://www.zdnet.com/new-usb-plug-coming-good-news-bad-news-7000023935/
>
> --Bob.
>
>
>
> On 13-12-09 11:17 PM, unsolicited wrote:
>> Just how much CPU power does it take to keep a (USB? eSata?) disk fed,
>> anyways?
>>
>> (Guess it depends if you're running something checksumming, like BTRFS,
>> I suppose, too?)
>>
>> I've seen some mirroring (striping?) external USB boxes, but I wonder if
>> catching a multi-GB rsync feed nightly would be beyond a Pi.
>>
>> Note: My question, not Khalid's. Different beastie.
>>
>> Are there other 'Pi' beasties out there?
>>
>>
>> On 13-12-09 10:22 PM, Khalid Baheyeldin wrote:
>>> I am considering building a small server that would have a largish USB
>>> disk. The server would be rsynced from the main server, and runs minidlna
>>> for access to photos, videos, music, ...etc.
>>>
>>> The Raspberry Pi seems like a good platform for this, being low power and
>>> runs Linux.
>>>
>>> Online sites are selling kits that include a power supply, SD card
>>> preloaded with NOOBS, and a case as well.
>>>
>>> So, the question is, anyone here order Raspberry Pis? Where did you order
>>> it from? Canadian or USA based? Did they ship on time? Did you pay
>>> customs?
>>>
>>> Looking for experiences, sites to avoid/recommend, ...etc.
>>>
>>> Examples I saw are Amazon, and this
>>> http://canada.newark.com/raspberry-pi-accessories
>>>
>>>
>>>
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>>> kwlug-disc at kwlug.org
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>>>
>>
>>
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