[ovirt-users] Someone can give me advice about Ovirt?

[Yedidyah Bar David]

On Tue, Sep 5, 2017 at 10:33 AM, Khoi Thinh <thinhduckhoi at gmail.com> wrote:
> Hi everyone,
> Here's my use case of using Ovirt
>
> I want to store only virtual machine of "Hosted engine" to Shared Disk, in
> addition i also want to store other virtual machine to "Local disk"

Generally speaking this is not supported. See also:

https://www.ovirt.org/develop/release-management/features/storage/mixed-types-data-center/
https://www.ovirt.org/develop/release-management/features/storage/decommission-master-domain-and-spm/

The closest thing you can use is the localdisk vdsm hook:

https://github.com/oVirt/vdsm/blob/master/vdsm_hooks/localdisk/README

> For "Hosted engine", i want to built it with High Availability.
> There's no need for High Availability for other virtual machine.
> Because i want to use HDD's capacity of Host server, so i'm considering the
> above-mention structure/design.
>
> What do you think about this? Any advice/thoughts would be appreciate.

Is your only reason being that you want to use the (presumably large,
fast, cheap) local disk instead of the (small or slow or expensive)
shared storage?

You can use also other means to achieve the same. Many people these days
use gluster, some use, or at least tried, other technologies - e.g. ceph, drbd,
gfs2, ocfs2 - search the list archives. Most, if not all, of these, are meant
to provide HA storage using local disks, and therefore waste more total storage,
compared to "just" use the local disk for local VMs.

You can also use the following hack:

1. On each of your hosts, create two VMs using other means (e.g. virsh),
and configure them to allow nested-kvm. One small, which will be used for the
hosted-engine hosts, and one large, for the other hosts' VMs
2. Deploy hosted-engine on the small VMs with your shared storage.
3. Add the large VMs as hosts with local storage
4. Then create your VMs on whatever DC/cluster you want - HA ones on the
small VMs (or just keep them only for the hosted-engine vm), others on
one of the local-disk hosts.

Best,
-- 
Didi