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by jkot
3973 days ago
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There was similar post with ARM Chromebooks. A few years ago it was impossible to find stable ARMs which could sustain decent load without crashing. Company had to buy bunch of Chromebooks, strip batteries and put them into rack. |
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Well, no. The guy putting that rack together didn't know what he was doing and insisted on using the stock AC adapter for the devices. You NEVER use the stock AC adapters in a cluster. They are (usually) made to be cheap and not operate at full load. Maybe 5% will fail under continuous full load. Put 16 in a cluster and now you are looking at a 60% chance of a single failure.
ALWAYS ditch the bundled AC adapter and use a single, good quality, high power PSU that branches out to all the boards. 5 volts and 40 amps, for example. These PSUs are more like 99.9% reliable, and as a bonus output much cleaner power.
The only reason that this guy had success with Chromebooks is because laptop PSUs are typically sized at 3x capacity (for battery charging). Running a stock PSU 24x7 but only at 30% output greatly reduces the failure rate.
edit:
http://www.systemcall.eu/blog/2014/06/trashing-chromebooks/
https://news.ycombinator.com/item?id=7876235
Besides ignoring the power supplies, the original author used SD cards on the HK boards instead of eMMC, which is another reliability no-no. Though HK is pretty good about shipping quality PSUs with their hardware, so I suspect it was uSD being flaky in this guy's case.