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

Wed Mar 25 07:35:28 EDT 2015

----- Original Message -----
> From: "Eric Wong" <Eric.Wong at solvians.com>
> To: "Simone Tiraboschi" <stirabos at redhat.com>
> Cc: users at ovirt.org
> Sent: Wednesday, March 25, 2015 12:12:47 PM
> Subject: RE: [ovirt-users] Hosted Engine config in our hardware environment
> 
> Simone:
> 
> I discussed with our SAN guy.  We currently is not able to configure the SAN
> in D1 & X1 to be seen by blades in both sides.  So we are pretty much stuck
> with our current ovirt mgmt. vms configuration.

That is not an hosted engine issue, it's a design issue.
If you want to provide HA or disaster recovery capabilities between your two racks both of them should be able to access your shared storage otherwise you simply cannot directly migrate a VM from D1 to X1 or viceversa.
If you have two racks with two different and insulated SAN and they cannot access each other you have two distinct insulated systems and you could only manage them as that; you could use a single oVirt engine for that but the engine VM itself could not migrate to the other system by design.

> I guess the main concern is how to control all the virtual machines with
> oVirt infrastructure if both our ovirt-mgmt vms went down, how can we start
> them up again. That also applies to any virtual machines.  If the oVirt
> mgmt infrastructure is not able, I think there is no way to start a VM,
> correct?

At low level you could directly use virsh directly on the host to start a VM directly over libvirtd but it's really a extreme solution.

> Again, Many Thanks,
> Eric
> 
> 
> -----Original Message-----
> From: Simone Tiraboschi [mailto:stirabos at redhat.com]
> Sent: Tuesday, March 24, 2015 5:11 PM
> To: Eric Wong
> Cc: users at ovirt.org
> Subject: Re: [ovirt-users] Hosted Engine config in our hardware environment
> 
> 
> 
> ----- Original Message -----
> > From: "Eric Wong" <Eric.Wong at solvians.com>
> > To: "Simone Tiraboschi" <stirabos at redhat.com>
> > Cc: users at ovirt.org
> > Sent: Tuesday, March 24, 2015 9:36:11 AM
> > Subject: RE: [ovirt-users] Hosted Engine config in our hardware environment
> > 
> > Simone:
> > 
> > Thanks for your quick respond.  It clarified some of the confusion I have
> > with the hosted-engine.
> > 
> > However, I still have one question.  Sorry.  It is my bad that I did not
> > explain clearer on our hardware configuration, mainly on the SAN.  We also
> > have 2 SAN, one on D1 & another one on X1.  The blades on D1 can only see
> > the storage in SAN D1.  X1 blades can only see SAN X1.
> > 
> > Does it mean that we will need to manage our oVirt environment separately
> > when we switch to use hosted-engine?  Because from your explanation, the
> > hosted-engine in selected nodes will use separate iSCSI hosted-engine
> > storage to store the DB.
> 
> With hosted engine not only the DB but all the engine VM is going to be
> stored on a dedicated iSCSI LUN so each host involved (not managed by) in
> hosted-engine should be able to access that device in order to be able to
> start the engine VM after other host failures.
> 
> So, if you want to have it restarting the engine VM on a X1 host after a
> complete failure of D1 rack, you need to store the engine VM on a location
> that is accessible both by D1 and X1.
> NFS could be an option too.
> Otherwise you should check your storage path design in order to have a cross
> rack path; you could also evaluate iSCSI multipathing.
> 
> 
> > Since there is no cross D1 & X1 storage in our
> > current config, that means we need separate hosted-engine setup on each
> > side.
> > 
> > Thanks,
> > Eric
> > 
> > 
> > -----Original Message-----
> > From: Simone Tiraboschi [mailto:stirabos at redhat.com]
> > Sent: Friday, March 20, 2015 7:06 PM
> > To: Eric Wong
> > Cc: users at ovirt.org
> > Subject: Re: [ovirt-users] Hosted Engine config in our hardware environment
> > 
> > 
> > 
> > ----- 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.
> > 
> > Here you can find some hint about how to migrate to hosted-engine:
> > http://www.ovirt.org/Migrate_to_Hosted_Engine
> > 
> > > 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?
> > > - How can we achieve redundancy when running Hosted Engine? We need to
> > > have
> > > management capibility in case one side completely failed.
> > > 
> > > Thanks in advance.
> > > Eric
> > > 
> > > _______________________________________________
> > > Users mailing list
> > > Users at ovirt.org
> > > http://lists.ovirt.org/mailman/listinfo/users
> > > 
> > 
> 