I just have a general question. Under what circumstances would it be helpful/useful to have more than one hub? I have a large home, three floors, with my one hub on the middle floor toward the back. I have about 70 devices of various types (sensors, switches, outlets, google home devices, sonos, blah blah blah). For the most part everything works OK, but I have noticed of late that certain apps will work intermittently or not at all (like mirroring functions), there are delays in some situations, etc. One couple of colored LEDs that I activate under motion in the foyer at sunset until 10pm or so with a white light, and then from then until sunrise I have them colored red under motion (red seems to be easier on sleep). These lights sometimes will stay white when they should be red, or vice versa. Anyway, several "first world" type problems. So I was wondering whether an additional hub would help. The other thing that is on a different topic is the Google Home app. I have 4 Minoston Z-Wave Dimmer Plug Outlets that are in my device list and work fine from Hubitat, but don't automate or even show up in Google Home anymore. And they used to. Can't figure out whether it's a Hubitat problem or a Google Home problem. Something changed over the last year or so.
There's no single reason to go beyond a single hub, it's usually a combination of reasons. Physical distances is one, if you have a shed or other detached building, then that distance will often be better served by a network extension than trying to get a mesh to work. Multiple floors would perhaps benefit, it does in my home. I've split my home into 3 physical 'slices' with a hub in each and I've offloaded all the Internet facing devices to a hub with no radios enabled.
I have been using multiple hubs for quite a while and Hubitat's Hub Mesh is an easy method of interconnecting. I personally gave myself a limit of 65 Z-Devices on a single hub. No special reason for "65" -- except by that point, I've got enough invested in those 65 devices to make the purchase of another hub a small incremental investment.
I can't speak to your Google Home issue.. I have one but it is exclusively used for Announcements.
And yes, I'm still using HubConnect because it's not broken 
I can't get myself interested in doing many hours of work to end up exactly where I am. 
One thing I would say to go along with what csteel said is that it is somewhat different for everyone as each if us have slightly different setups.
It all varies based on the mix of hub attached devices with zwave and zigbee, wifi cloud services attached, and then just lan connected devices that are on our local network. Theoretically zwave supports 255 devices on one hub while zigbee supports in the range of many thousand. To get reliably on either you need a good combination of repeating devices to build out your mesh. If tou don't you may find occasions where a second hub could be useful as well to make allot of batter powered devices be more reliable.
Wifi and cloud devices can have a wide variety of impacts on a hub that depend allot on their driver and how the devices work. Pooling for status from wifi devices can be rather intensive and put a hurting on the hubs cpu.
Rokus are a good example about that. I use the integration for roku and the guy that wrote it did a great job, it just take allot of cpu to query the roku api to get states if you want to do actions based on the current state of a used device.
Ultimately you need to just get to know your environment and then decide if it would be beneficial.
Have you tried removing them from the google home app on your hub and adding them back?
@mavrrick58 In the Hubitat Google Home app, if I enter the four devices in question (specifically, Minoston MP21ZD Z-Wave Mini Plug Dimmer), I am able to check them and update the list and then click done. But they never show up in Google Home, and when I go back to look at the list in the Hubitat Google Home app, they are unchecked as if I had never added them. To be fair, at the top of the Google Home app page it says " If you include a device that isn't compatible with Google Home it will just be ignored and not sent to Google Home." So, on re-pondering the problem, it seems that something has changed on the Google Home side and that is has nothing to do with the Hubitat environment.
@csteele I am a journeyman-level programmer from the 1980s, so am slightly competent, but am very much a dinosaur. Meaning at age 76 my brain is full and I am increasingly less inclined to want to learn something new. Maybe not as bad as that sounds. My devices on the Hubitat are mainly Zigbee and Z-Wave. I no longer have any WiFi switches or outlets connected to the Hubitat environment unless it is through an app that someone has built. I still have a handful of devices hooked up to my old SmartThings Hub for those situations where I have been too lazy to convert them to ZB or ZW. I don't really understand what you meant by your last sentence in that first paragraph ("...3 physical slices...a hub with no radios enabled..."). Can you give me a specific example of that hub using a couple of devices to exemplify what you mean? My only challenge for adding a hub on each floor is that I don't have ethernet on floor 3. I've been meaning to figure out how to string some cable up there, but so far haven't. My home network consists of a separate modem, separate non-wireless router, and five wireless access points (definitely overkill toys). Maybe I've got RF saturation. I have recently dialed down the signal strength on all the WAPs to about half power. My hub is connected to one of my switches. I guess I need to read up on how I would add another Elev hub if I wanted to, and figure out how I would allocated the client devices to the two hubs.
One reason I might try a second hub is in case that enabled me to have Aqara devices with their own network and not drop off all the time. Thing is it's a bit of an expensive experiment as I am not optimistic of the success.
If you look at my drawing, there's 3 hubs that show ZWave, one with Zigbee and a 4th that shows neither. (far right) That's the hub that has no ZRadios enabled, it's got enough to do to handle the internet facing devices. (Google Home, Alexa, Weather, etc) It also handles my LAN connected devices such as Lifx and Shelly. Dashboards have been created but I rarely use them, but there's LAN traffic generated regardless.
The three hubs that do have Z-devices are for "downstairs", "upstairs" and "front" (Front is a newish C-7 I added to migrate devices from upstairs/downstairs that are in an imaginary vertical slice across the first third of my house.) The intent is to have up to 65 Z-devices per hub. Resulting in:
- 57 zwave; 0 zigbee; 107 total devices C-5
- 25 zwave; 23 zigbee; 69 total devices C-5
- 0 zwave; 0 zigbee; 163 total devices C-7
- 33 zwave; 0 zigbee; 50 total devices C-7
Hat tip to your 80's legacy. A lot of us were there.
As far as multiple hubs, I'm right on that remote building justification and quite frankly it is kinda nice not worrying about reliance on ONE HUB.
BUT, if all my stuff was under one roof I would not be inclined to run multiple hubs. In my mind that should not be a requirement. I would put repeaters everywhere.
Would I have a second hub that I keep "hot" and ready to replace the main one should it die or be harmed, probably so due to the single point of vulnerability and my increasing dependence on the system.
But for all this, "put this stuff on one, that stuff on another" I'd rather not have "the stuff" that requires separation for optimal operation. I am RESISTING this being my HOBBY !
To be more specific here are some of the reasons I know of.
-
Physically separated structures:
Think of this like a workshop or large shed or bard you want to automate. It is likely it may be separated from your house enough you can't get directly to the hub, and you will have very limited options for the mesh to reach it. -
Separated Perm HA environment from your dabbling/dev environment:
Think of this like a way to maintain a good WAF/SAF(wife acceptance factor/Spouse acceptance factor). You can implement ideas in a testing environment and ensure they don't impact your day to day automations everyone depends on. -
Separate connectivity technologies:
This would be with the intent of separating Zwave, Zigbeee, and Wifi. This has potential benefits depending how reliable each network is, or if you have particular devices that can cause issues with the hub, Some manufactures also don't fully implement Zigbee standards and as such can cause problems with other devices on that network. Putting such devices on their own hub can make everything more reliable. Not all wifi devices are created equal and can be very chatty and make the hub slower as well. -
Dedicated Smartapp/Cloud integration hub.
This is when you separate all integrations and smartapps to ensure max speed and reliability to control devices. Cloud and Wifi devices tend to be chatty and cpu intensive. Moving these devices off to their own hub helps maximize performance. For Zwave and Zigbee devices by preventing potential long cpu spikes that can occur with devices on wifi or cloud based integrations. Two potential examples of this are the Action Tiles integration, or Ecobee Suite. These two cloud based services are generally my top consumers on my hub for CPU. -
Construction materials cause interference: This is much like item 1 in this list, but has to do with simple limitations of your how structure in the walls and such that make RF a problem in general.
When it all comes down to it you are really just trying to manage one thing, and that is quick fast actions on devices. The best way to do that is to ensure your devices have good healthy paths to the hub and that the hub is not to busy. Pretty much everyone of these items I mentioned are about that except for the reason to protect WAF. I personally would try to keep the number of hubs to a minimum like @PunchCardPgmr suggests, but i also wouldn't say you should worry about running more then one if you start to see any issues.
I do run a second so I can test new ideas and ensure i don't impact my main hub. I have had found a few occasions where i can create self inflicted problems by killing the hub cpu. Maintaining a good WAF is critical for me to be able to keep doing more HA.
For reference I have about 21 Zigbee devices 37 Zwave devices a slew of Wifi devices and a handful of virtual devices for a total of 114 on a Single hub. It runs reliably for my situation. Probably have of my zwave and zigbee devices are repeaters.
Thanks for all your responses. They give me more things to ponder. My ponder basket is starting to overflow, so I better start moving some items from the ponder stage to the execution stage or to the rubbish bin of wild ideas.
