On Thu, Jan 17, 2019 at 1:40 AM Ryan Barry <rbarry@redhat.com> wrote:
Re-raising this for discussion.

As I commented on the bug, Hosted Engine is such a special use case in terms of setup, configuration, and migration that I'm not sure engine itself is the right place to handle this. We have the option of changing the ha broker|agent to use the engine API to initiate migrations, but there's still a risk that the hosts in the secondary cluster will not be able to reach the storage, etc.

It would be great to get this resolved if there's not currently a way to do it, but we need to decide on a long-term direction for it. Currently, HE can run on additional hosts in the datacenter as an emergency fallback, but it reverts once the HE cluster is back out of maintenance. My ideal would be to extend the hosted-engine utility with an additional parameter which reaches out to the Engine API in order to handle the needed database updates after some safety checks (probably over ansible) to ensure that the HE storage domain is reachable from hosts in the other cluster.

But I'm not a hosted engine expert. Is there currently a way to do this? If there isn't, do we want to add additional logic to ha agent|broker, or reach out to the Engine?

Currently on hosted-engine-side we are not saving engine credentials at all so there is really no way to trigger any automatic action over engine API.

Personally I'm neither persuaded that having the hosted-engine VM floating here and there across different clusters is a good idea: the cluster concept is there to enforce that a set of hosts have a set of shared features and run on a compatible version.
If we decide to ignore that constraints we can open the door to a lot possible issues.

What we can instead do is provide an ansible playbook or something like that to definitively migrate the engine VM to a different cluster on the next book.
I fear it could require to directly edit the DB and reboot the engine VM.
 

On Tue, Jan 15, 2019 at 8:27 AM Douglas Duckworth <dod2014@med.cornell.edu> wrote:
Hi

I opened a BugZilla at https://bugzilla.redhat.com/show_bug.cgi?id=1664777 but no steps have been shared on how to resolve.  Does anyone know how this can be fixed without destroying the data center and building a new hosted engine?

Thanks,

Douglas Duckworth, MSc, LFCS
HPC System Administrator
Scientific Computing Unit
Weill Cornell Medicine
1300 York Avenue
New York, NY 10065
E: doug@med.cornell.edu
O: 212-746-6305
F: 212-746-8690


On Wed, Jan 9, 2019 at 10:22 AM Douglas Duckworth <dod2014@med.cornell.edu> wrote:
Hi

Should I open a Bugzilla to resolve this problem?

Thanks,

Douglas Duckworth, MSc, LFCS
HPC System Administrator
Scientific Computing Unit
Weill Cornell Medicine
1300 York Avenue
New York, NY 10065
E: doug@med.cornell.edu
O: 212-746-6305
F: 212-746-8690


On Wed, Dec 19, 2018 at 1:13 PM Douglas Duckworth <dod2014@med.cornell.edu> wrote:
Hello

I am trying to migrate my hosted-engine VM to another cluster in the same data center.  Hosts in both clusters have the same logical networks and storage.  Yet migrating the VM isn't an option.

To get the hosted-engine VM on the other cluster I started the VM on host in that other cluster using "hosted-engine --vm-start."  

However HostedEngine still associated with old cluster as shown attached.  So I cannot live migrate the VM.  Does anyone know how to resolve?  With other VMs one can shut them down then using the "Edit" option.  Though that will not work for HostedEngine.


Thanks,

Douglas Duckworth, MSc, LFCS
HPC System Administrator
Scientific Computing Unit
Weill Cornell Medicine
1300 York Avenue
New York, NY 10065
E: doug@med.cornell.edu
O: 212-746-6305
F: 212-746-8690
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--

Ryan Barry

Associate Manager - RHV Virt/SLA

rbarry@redhat.com    M: +16518159306     IM: rbarry