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i've built a 25 node rpi cluster with a ups for the rpis. but not for the ethernet switch. does turning off my gigabit impact my cluster? if yes, please tell me what i can do about it.

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    No information has been provided with which to give an answer. The Pi seems pretty irrelevant to this question.
    – joan
    Commented Jul 29, 2021 at 16:01
  • seriously? look, i've faced a disaster when my pi's sd card got corrupt because of a power cut. i don't want this to happen again.
    – user135142
    Commented Jul 29, 2021 at 16:31
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    what you say makes no sense ... if you are so worried about it, then power the switch from the UPS
    – jsotola
    Commented Jul 29, 2021 at 21:23

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Your question is vague and lacking direction and you have given no details about the software you are running or what the cluster does, but let's see if we can enumerate the possibilities. Will powering down the switch impact the cluster? Here's a list of possible ways it could impact it:

  • Hardware: ethernet is designed to be disconnected while powered on. As long as powering it off doesn't cause a power spike in the network cable, the hardware should be fine.
  • Operating system integrity: the system should not crash, but if you have shared services between pis, those may hang or timeout while the switch is down; if they hang, most services should recover when the network is restored, but it depends on the service
  • SD cards: as long as the operating system doesn't crash, or is at least shut down cleanly, the SD cards shouldn't be corrupted
  • Network connections: Obviously, when the switch is off, there is no network traffic. TCP/IP is designed to handle this to some extent. TCP connections with no traffic on them might not notice, but if anything tries to send data with the network down, TCP connections may time out and disconnect after 30 seconds. UDP and other packet based protocols may have their own timeouts.

Have I missed anything you are concerned about? And, as already pointed out, why not put the switch on the UPS too?

Note that part of the purpose of a UPS is to filter spikes from the power line (possibly from lightning strikes or other sources). By not putting the switch on the UPS, you could be introducing those power spikes through the network lines to the PIs.

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  • ok @user10489 .
    – user135142
    Commented Jul 30, 2021 at 8:30
  • one more thing @user10489 - And, as already pointed out, why not put the switch on the UPS too? cant find a 25 (or 26) port gigabit powered through usb 5v. i'm using piz uptime ups.
    – user135142
    Commented Jul 30, 2021 at 8:43
  • thanks for the large explanation.
    – user135142
    Commented Jul 30, 2021 at 8:48
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Maybe? It will not damage the hardware which has been designed to tolerate that. As far as software that is an entirely different arena and is dependent on the programs themselves. Some may just sit there and come back when the switch comes back up, some may hang, and some may just shut down. I have no way of knowing as I have no idea of what programs (tasks) are running on your server and remotes.

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  • will the software fail or something? that's the main thing about this question. if yes, what can i do about it?
    – user135142
    Commented Jul 30, 2021 at 3:20
  • and i want to run ubuntu desktop.
    – user135142
    Commented Jul 30, 2021 at 3:25
  • I cannot say if the software will fail or not, you have to get that information from the software source. Ubuntu is a great operating system, I use it all the time. I use it for software development for some of my toys. I routinely unplug and plug in the USB and Ethernet cables without any problems. I have pulled the plug a few time and so far have been lucky no damage or problems other then losing an open file but the backup was there.
    – Gil
    Commented Jul 30, 2021 at 3:49

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