[ovirt-users] Re: oVirt install questions

22 Jun 2020

      Hey David,

keep in mind that you  need some big NICs.
I started  my oVirt lab with 1 Gbit  NIC and later added 4 dual-port  1 Gbit  NICs  and I had to create multiple  gluster volumes  and multiple storage domains.
Yet,  windows  VMs cannot use software  raid  for boot devices,  thus it's a  pain in the @$$.
I think that optimal is to have several 10Gbit NICs (at least  1  for gluster and 1 for oVirt live migration).
Also,  NVMEs  can be used  as lvm cache for spinning disks.

Best Regards,
Strahil  Nikolov

На 22 юни 2020 г. 18:50:01 GMT+03:00, David White <dmwhite823@protonmail.com> написа:
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For migration between hosts you need a shared storage. SAN, Gluster,
CEPH, NFS, iSCSI are among the ones already supported (CEPH is a little
bit experimental).
Sounds like I'll be using NFS or Gluster after all.
Thank you.
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The engine is just a management layer. KVM/qemu has that option a
long time ago, yet it's some manual work to do it.
Yeah, this environment that I'm building is expected to grow over time
(although that growth could go slowly), so I'm trying to architect
things properly now to make future growth easier to deal with. I'm also
trying to balance availability concerns with budget constraints
starting out.
Given that NFS would also be a single point of failure, I'll probably
go with Gluster, as long as I can fit the storage requirements into the
overall budget.
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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Monday, June 22, 2020 6:31 AM, Strahil Nikolov via Users
<users@ovirt.org> wrote:
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На 22 юни 2020 г. 11:06:16 GMT+03:00, David White via
Usersusers@ovirt.org написа:
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Thank you and Strahil for your responses.
They were both very helpful.
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I think a hosted engine installation VM wants 16GB RAM configured
though I've built older versions with 8GB RAM.
For modern VMs CentOS8 x86_64 recommends at least 2GB for a host.
CentOS7 was OK with 1, CentOS6 maybe 512K.
The tendency is always increasing with updated OS versions.
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Ok, so to clarify my question a little bit, I'm trying to figure
out
how much RAM I would need to reserve for the host OS (or oVirt
Node).
I do recall that CentOS / RHEL 8 wants a minimum of 2GB, so perhaps
that would suffice?
And then as you noted, I would need to plan to give the engine
16GB.
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I run my engine on 4Gb or RAM, but i have no more than 20 VMs, the
larger the setup - the more ram for the engine is needed.
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My minimum ovirt systems were mostly 48GB 16core, but most are
now
128GB 24core or more.
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But this is the total amount of physical RAM in your systems,
correct?
Not the amount that you've reserved for your host OS?I've spec'd
out
some hardware, and am probably looking at purchasing two PowerEdge
R820's to start, each with 64GB RAM and 32 cores.
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While ovirt can do what you would like it to do concerning a
single
user interface, but with what you listed,
you're probably better off with just plain KVM/qemu and using
virt-manager for the interface.
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Can you migrate VMs from 1 host to another with virt-manager, and
can
you take snapshots?
If those two features aren't supported by virt-manager, then that
would
almost certainly be a deal breaker.
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The engine is just a management layer. KVM/qemu has that option a
long time ago, yet it's some manual work to do it.
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Come to think of it, if I decided to use local storage on each of
the
physical hosts, would I be able to migrate VMs? 
Or do I have to use a Gluster or NFS store for that?
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For migration between hosts you need a shared storage. SAN, Gluster,
CEPH, NFS, iSCSI are among the ones already supported (CEPH is a little
bit experimental).
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‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Sunday, June 21, 2020 5:58 PM, Edward Berger edwberger@gmail.com
wrote:
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While ovirt can do what you would like it to do concerning a
single
user interface, but with what you listed,
you're probably better off with just plain KVM/qemu and using
virt-manager for the interface.
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Those memory/cpu requirements you listed are really tiny and I
wouldn't recommend even trying ovirt on such challenged systems.
I would specify at least 3 hosts for a gluster hyperconverged
system,
and a spare available that can take over if one of the hosts
dies.
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I think a hosted engine installation VM wants 16GB RAM configured
though I've built older versions with 8GB RAM.
For modern VMs CentOS8 x86_64 recommends at least 2GB for a host.
CentOS7 was OK with 1, CentOS6 maybe 512K.
The tendency is always increasing with updated OS versions.
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My minimum ovirt systems were mostly 48GB 16core, but most are
now
128GB 24core or more.
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ovirt node ng is a prepackaged installer for an oVirt
hypervisor/gluster host, with its cockpit interface you can
create and
install the hosted-engine VM for the user and admin web
interface.  Its
very good on enterprise server hardware with lots of RAM,CPU, and
DISKS.
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On Sun, Jun 21, 2020 at 4:34 PM David White via Users
users@ovirt.org wrote:
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I'm reading through all of the documentation at
https://ovirt.org/documentation/, and am a bit overwhelmed with
all of
the different options for installing oVirt.
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My particular use case is that I'm looking for a way to manage
VMs
on multiple physical servers from 1 interface, and be able to
deploy
new VMs (or delete VMs) as necessary. Ideally, it would be
great if I
could move a VM from 1 host to a different host as well,
particularly
in the event that 1 host becomes degraded (bad HDD, bad
processor,
etc...)
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I'm trying to figure out what the difference is between an
oVirt
Node and the oVirt Engine, and how the engine differs from the
Manager.
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I get the feeling that `Engine` = `Manager`. Same thing. I
further
think I understand the Engine to be essentially synonymous with
a
vCenter VM for ESXi hosts. Is this correct?
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If so, then what's the difference between the `self-hosted` vs
the
`stand-alone` engines?
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oVirt Engine requirements look to be a minimum of 4GB RAM and
2CPUs.
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oVirt Nodes, on the other hand, require only 2GB RAM.
Is this a requirement just for the physical host, or is that
how
much RAM that each oVirt node process requires? In other words,
if I
have a physical host with 12GB of physical RAM, will I only be
able to
allocate 10GB of that to guest VMs? How much of that should I
dedicated
to the oVirt node processes?
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Can you install the oVirt Engine as a VM onto an existing oVirt
Node? And then connect that same node to the Engine, once the
Engine is
installed?
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Reading through the documentation, it also sounds like oVirt
Engine
and oVirt Node require different versions of RHEL or CentOS.
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I read that the Engine for oVirt 4.4.0 requires RHEL (or
CentOS)
8.2, whereas each Node requires 7.x (although I'll plan to just
use the
oVirt Node ISO).
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I'm also wondering about storage.
I don't really like the idea of using local storage, but a
single
NFS server would also be a single point of failure, and Gluster
would
be too expensive to deploy, so at this point, I'm leaning
towards using
local storage.
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Any advice or clarity would be greatly appreciated.
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Thanks,
David
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