[ovirt-users] Hosted Engine config in our hardware environment

[Simone Tiraboschi]

----- Original Message -----
> From: "Eric Wong" <Eric.Wong at solvians.com>
> To: users at ovirt.org
> Sent: Thursday, March 19, 2015 7:04:04 PM
> Subject: [ovirt-users] Hosted Engine config in our hardware environment
> 
> Hello oVirt guru out there:
> 
> I want to seek some advice on upgrade path for our oVirt management vm
> configuration. We have been using oVirt for over 3 years. When we first
> setup oVirt environment, Hosted Engine componment did not exist. Our
> question is should we migrate our current configuration to use Hosted
> Engine?
> 
> First let me give an overview of our configuration. We have blade servers in
> 2 separate racks. D1 & X1. Each side has 10 blades. Storage is iSCSI SAN.
> 
> Inside our oVirt 3.5.0.1-1.el6 installation, it is configured with 2 data
> centers. D1 & X1. Each datacenter has the 10 blades for that side. The
> management function of oVirt (oVirt web console) is running off 2 VMs,
> ovirt-mgmt-1 on D1, and ovirt-mgmt-2 on X1. We have keepalived to maintain a
> flowing IP for the oVirt management console. The keepalived script makes
> sure only one copy of ovirt-engine is running at any time. It can be on D1
> or X1. The mgmt VMs have Postgresql setup in replication mode. In case one
> of the mgmt vm failed, the other mgmt vm on the other rack can pick up the
> mgmt role. Both mgmt VMs can see all blades and SAN resources on D1 & X1.
> 
> This configuration has been working well for us. The drawback is if both
> ovirt mgmt vm crashed, we will not be able to start them or make any change
> to the ovirt environment. It is because the mgmt VMs are running within the
> oVirt domain.
> 
> We tried to upgrade our configuration to Hosted Engine configuration. From
> what I understand, the Hosted Engine will run in a separate storage domain.
> In both times we tried to upgrade to Hosted Engine, they both failed during
> export and import of current configuration.
> 
> I think my questions are:
> - will the Hosted Engine model works in our hardware configuration. With
> hardware in 2 racks, D1 & X1. Can a single Hosted Engine manage hardware on
> both sides?

Yes it can.

> - How can we achieve redundancy when running Hosted Engine? We need to have
> management capibility in case one side completely failed.

With hosted engine you are going to have a single VM managing three data-center: D1, X1 and an hosted-engine specific one.
The hosted-engine datacenter will use an additional shared storage domain (with 3.5 iSCSI is fine) dedicated to hosted engine. On each host you are deploying hosted-engine on (2 o 3 hosts), an agent for HA will be installed: it's up to that agent to monitor the status on the engine VM and restart it (with the needed locking mechanism to have just one copy of it running) if the host were it was previously running has crashed.
So ovirt-hosted-engine-ha will ensure HA for the engine VM without the need to have to copy of that with a replicated DB.

> Thanks in advance.
> Eric
> 
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