Running Dual NAC's

Discussion in 'C-Bus Automation Controllers' started by pgardiner, Feb 8, 2021.

  1. pgardiner

    pgardiner

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    Have a client who wants to run 2 NAC's on the same system.

    I know it needs different IP and Different device ID's but any reason why this will not work?

    He wants to add redundancy across a very complicated network. Split resources in case one NAC dies and then at least some of the whole house will still run.

    It’s very an automation heavy config.
     
    pgardiner, Feb 8, 2021
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  2. pgardiner

    Pie Boy

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    2 or More NAC can exist on the same cbus network this would work although
    Depends what you mean when you say redundancy, if you mean
    if one falls over the other one takes control then that would be possible although i think its getting very complicated,
    or if you mean put in two Nacs because the CPU load is too high for one and you need to spread the load?
    you should consider what is causing the high cpu load before adding another NAC
     
    Pie Boy, Feb 8, 2021
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  3. pgardiner

    pgardiner

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    Thanks for reply.

    Load is not an issue, he just wants to spread the likely hood of faulire accorss 2 NACS.
    He works away from home a lot and doesnt want a single point of fauilure to take the whole house off line with a dead NAC.
    For example (analogy) when I configure a room with several lighting circuits I wire the circuits over more than 1 Dimmer module, if a dimmer fails then at least there is some control in that room.
     
    pgardiner, Feb 9, 2021
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  4. pgardiner

    pgardiner

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    As a side note, is there a config that can automate NAC redundancy, ie run 2 NACs and set one or other to be live based on uptime?
     
    pgardiner, Feb 9, 2021
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  5. pgardiner

    Pie Boy

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    No not that I am aware of, if both are connected to cbus, both will react all cbus event/s

    If you don’t want to rely on one unit, and you want to put 2 nac in, the simplest way to do it would be to split the logic half in each unit etc

    In my opinion it seems excessive to put in 2 nac in this situation, it will be hard to remember which nac is doing what and easy to mistakenly double up (same script on both nac) would be a pain for fault finding...

    You would be better off building your project in such a way so it didn’t matter if the nac was to fail or go offline, thus not requiring the need for the redundancy

    Im Interested to know what some others think...
     
    Last edited: Feb 9, 2021
    Pie Boy, Feb 9, 2021
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  6. pgardiner

    Diggerz

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    You could pick one nac to be the master and the other to be the redundant slave, have the same configs in both but in the master nac add a schedule that regularly pulses a group address, this will be a heartbeat status. In the slave have all schedules / logic / scenes disabled. Then set up a script that polls the master nac’s status group address. If the group hasn’t been triggered after a period of time have a script activate all schedules, logic, scenes in the redundant NAC, maybe even add in an email notification or graphic to indicate the main nac is down.

    Once the status group is back up have the slave disable everything again

    do agree its probably overkill to have 2 NAC’s but if the client is set on it this may be a solution?
     
    Last edited: Feb 10, 2021
    Diggerz, Feb 10, 2021
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  7. pgardiner

    lcrowhurst

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    What about have the first nacs relay output active when it’s booted, have the second nacs power supply run through the first Mac normally closed contact. So once the first nac is up and running the normally closed output is opened and power is cut to the second nac . If the first Nac fails (or it’s power supply) , then the normally closed relay will close , powering up the second Nac.

    that way you can have identical programming on each.
     
    lcrowhurst, Feb 10, 2021
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  8. pgardiner

    chromus

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    Unless this guy is running medical equipment this is crazy, if the NAC fails the worst that happens is he loses remote access and/or some logic.

    The chances of it failing are very very slim and you would be better having a 2nd CNI (or Wiser2 for logic) so you can get in remotely and fix things rather than 2 whole NACs.

    I understand some redundancy, I have a very large marine aquarium and run it off multiple phases and circuit breakers to ensure that if 1 fails I should have the rest of the temperature and water movement available.

    The weakest link isn't the CBUS gear, it's going to be input power. If that goes you lose the lot until its restored anyway.
     
    chromus, Feb 18, 2021
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  9. pgardiner

    Damaxx

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    Have to agree chromus - cheaper option would be to do all automation's with Node Red on a couple of Raspberry pi's with automatic failover.

     
    Damaxx, Feb 18, 2021
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  10. pgardiner

    zei20t

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    node red is awesome, so versatile. having redundancy is overkill for me, but being able to talk to other instances of NR and passing on data is great!
     
    zei20t, Feb 19, 2021
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