With this update, the user can configure the number of memory slots reserved for spare self-hosted engines instances if the current host crashes. Previously, there was a chance that the self-hosted engine virtual machine would not have a place to start on a loaded cluster and this compromised the high availability feature. Now, the self-hosted engine will have a place start a backup host so that it is ready to accept the virtual machine is the current host crashes. This will require some edits to the self-hosted engine installation procedure.
*** Bug 1436613 has been marked as a duplicate of this bug. ***
See bug 1436613 for additional details related to this feature.
The documentation for reserving memory on additional self-hosted engine hosts so that the Manager virtual machine can migrate has now been published: https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.1/html-single/self-hosted_engine_guide/#Configuring_Memory_Slots_Reserved_for_the_SHE https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.1/html-single/administration_guide/#Configuring_scheduling_policy
Question to docs team: why I do not see this recommendation under recommendation setting here: https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.1/html/planning_and_prerequisites_guide/recommendations#self-hosted-engine-recommendations Question to engineering: why there is no default value for this? What happens when this value is not set and there is no host to run HE VM and the current is failing?
To be honest, there is no good reason from the engineering point of view. A default value of 1 would be a better default. We introduced this late and so we probably did not want to change the behaviour for existing setups.
(In reply to Marina from comment #15) > Question to docs team: why I do not see this recommendation under > recommendation setting here: > https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.1/ > html/planning_and_prerequisites_guide/recommendations#self-hosted-engine- > recommendations It's possible that this was completed before the Planning and Prerequisites Guide was created, and then did not get flagged as a recommendation when it was. Marina, would be be able to raise new BZ to request that this information is added to the Planning and Prerequisites Guide? We're targeting all new fixes now at 4.2.