Description of problem: When adding a host, if the user asks to deploy the host as a hosted-engine host, and we already have many such hosts, perhaps more than 7, warn the user that this isn't recommended. See also bug 2026625.
How much hosts is OK and after which exact number of hosts will user receive the warning message?
(In reply to Nikolai Sednev from comment #1) > How much hosts is OK and after which exact number of hosts will user receive > the warning message? The number '7' in comment 0 is already mentioned in our docs: https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.4/html-single/planning_and_prerequisites_guide/index#self-hosted-engine-recommendations https://access.redhat.com/articles/906543 I mentioned this in referenced bug 2026625 comment 1. Sorry for not mentioning this in comment 0 here.
So we'll have to try it with at least 8 ha-hosts, to be able to get the warning message. 7-should be added OK. 8-th should trigger the warning? Should 8-th ha-host still be added or the warning will also restrict adding additional 8-th ha-host?
I'd leave this to the bug owner to design/decide/split/consult/whatever. IMO warning is enough, no need to prevent. If we do prevent, we'll likely want to make this configurable (to allow testing, specific special cases, etc.), so likely more complicated. The design should probably include at least specifying manual/UI behavior (a popup?) and API (a notification? audit log? something else?).
BTW: Some time ago someone suggested somewhere also the opposite feature: If you add a host, and this is a hosted-engine setup, and you only have one HA host, you should get a warning suggesting to deploy HE HA on the host you are adding. Not sure if we ever did this. Might make sense to include this in current bug otherwise.
(In reply to Yedidyah Bar David from comment #5) > BTW: Some time ago someone suggested somewhere also the opposite feature: If > you add a host, and this is a hosted-engine setup, and you only have one HA > host, you should get a warning suggesting to deploy HE HA on the host you > are adding. Not sure if we ever did this. Might make sense to include this > in current bug otherwise. Sounds very logical to have at least 2 ha-hosts, although warning message could pretty annoying. (In reply to Yedidyah Bar David from comment #4) > I'd leave this to the bug owner to design/decide/split/consult/whatever. > > IMO warning is enough, no need to prevent. If we do prevent, we'll likely > want to make this configurable (to allow testing, specific special cases, > etc.), so likely more complicated. > > The design should probably include at least specifying manual/UI behavior (a > popup?) and API (a notification? audit log? something else?). Yes, looks like the whole RFE is about adding only a warning, I didn't follow it from the beginning. I suppose its for a scale team to verify, as it will require at least 8 ha-hosts, 7 should behave normally, adding of 8-th should trigger the warning, but continue normally and not cause any issues adding it or even more ha-hosts. IMHO warning should appear after adding 8-th and any additional to it, so warning will appear for 8-th, 9-th, 10-th and so on.
Technically speaking, we do allow many more hosts, see bug 1916032. Bug 1399613 was the original suggestion of comment 5 (mentioning also here because the link added with "Link ID" does not show anything when hovering above it, but here it does).
Verified in ovirt-engine-4.5.1.2-0.11.el8ev When adding new HE host, a warning log message is shown if the number of recommended HE hosts is exceeded (by default 7), e.g.: "There are 8 HE hosts deployed. Deploying more than 7 HE hosts isn't recommended. Please remove dead hosts, if any, in order to get rid of this warning" The default value can be changed via `MAX_RECOMMENDED_HE_HOSTS` variable in a config file put in /etc/ovirt-engine/engine.conf.d/ directory.