On 25/09/17 13:56, Simone Tiraboschi wrote:
On Sun, Sep 24, 2017 at 10:59 PM, Ben Bradley <list...@virtx.net
<mailto:list...@virtx.net>> wrote:
On 23/09/17 00:27, Ben Bradley wrote:
On 20/09/17 15:41, Simone Tiraboschi wrote:
On Wed, Sep 20, 2017 at 12:30 AM, Ben Bradley
<list...@virtx.net <mailto:list...@virtx.net>
<mailto:list...@virtx.net <mailto:list...@virtx.net>>> wrote:
Hi All
I've been running a single-host ovirt setup for several
months,
having previously used a basic QEMU/KVM for a few years
in lab
environments.
I currently have the ovirt engine running at the
bare-metal level,
with the box also acting as the single host. I am also
running this
with local storage.
I now have an extra host I can use and would like to
migrate to a
hosted engine. The following documentation appears to
be perfect and
pretty clear about the steps involved:
https://www.ovirt.org/develop/developer-guide/engine/migrate-to-hosted-engine/
<https://www.ovirt.org/develop/developer-guide/engine/migrate-to-hosted-engine/>
<https://www.ovirt.org/develop/developer-guide/engine/migrate-to-hosted-engine/
<https://www.ovirt.org/develop/developer-guide/engine/migrate-to-hosted-engine/>>
and
https://www.ovirt.org/documentation/self-hosted/chap-Migrating_from_Bare_Metal_to_an_EL-Based_Self-Hosted_Environment
<https://www.ovirt.org/documentation/self-hosted/chap-Migrating_from_Bare_Metal_to_an_EL-Based_Self-Hosted_Environment>
<https://www.ovirt.org/documentation/self-hosted/chap-Migrating_from_Bare_Metal_to_an_EL-Based_Self-Hosted_Environment
<https://www.ovirt.org/documentation/self-hosted/chap-Migrating_from_Bare_Metal_to_an_EL-Based_Self-Hosted_Environment>>
However I'd like to try and get a bit more of an
understanding of
the process that happens behind the scenes during the
cut-over from
one engine to a new/hosted engine.
As an experiment I attempted the following:
- created a new VM within my current environment
(bare-metal engine)
- creating an engine-backup
- stopped the bare-metal engine
- restored the backup into the new VM
- ran engine-setup within the new VM
The new engine started up ok and I was able to connect
and login to
the web UI. However my host was "unresponsive" and I
was unable to
manage it in any way from the VM. I shut the VM down
and started the
bare-metal ovirt-engine again on the host and
everything worked as
before. I didn't try very hard to make it work however.
The magic missing from the basic process I tried is the
synchronising and importing of the existing host, which
is what the
hosted-engine utility does.
No magic up to now: the host are simply in the DB you restored.
If the VM has network connectivity and the same host-name of
the old machine you shouldn't see any issue.
If you changed the host-name moving to the VM, you should
simply run engine-rename after the restore.
Thank you for the reply.
I tried this again this evening - again it failed.
The host is present within the new engine but I am unable to
manage it.
Host is marked as down but Activate is greyed out. I can get get
into the "Edit" screen for the host and on right-click I get the
following options:
- Maintenance
- Confirm Host has been Rebooted
- SSH Management: Restart and Stop both available
The VMs are still running and accessible but are not listed as
running under the web interface. This time however I did lose
access to the ovirtmgmt bridge and the web interface, running
VMs and host SSH session were unavailable until I rebooted.
Luckily I left ovirt-engine service enabled to restart on boot
so everything came back up.
The engine URL is a CNAME so I just re-pointed to the hostname
of the VM just before running engine-setup after the restore.
This time though I have kept the new engine VM so I can power it
up again and try and debug.
I am going to try a few times over the weekend and I have setup
serial console access so I can do a bit more debugging.
What ovirt logs could I check on the host to see if the new
engine VM is able to connect and sync to the host properly?
Thanks, Ben
So I tried again to migrate my bare-metal host to a hosted VM but no
luck. The host remained in unresponsive state in the engine web UI
and I was unable to manage the host in anyway. Although all VMs
continued to run.
I did capture some logs though.
From the new engine VM... engine.log
https://p.bsd-unix.net/view/raw/666839d1
<https://p.bsd-unix.net/view/raw/666839d1>
From the host...
mom.log https://p.bsd-unix.net/view/raw/ac9379f0
<https://p.bsd-unix.net/view/raw/ac9379f0>
supervdsm.log https://p.bsd-unix.net/view/raw/f9018dec
<https://p.bsd-unix.net/view/raw/f9018dec>
vdsm.log https://p.bsd-unix.net/view/raw/bcdcdb13
<https://p.bsd-unix.net/view/raw/bcdcdb13>
Sorry but no one of that links is working right now.
The engine VM is complaining about being unable to connect to the
host, though I can see from tcpdump communication is fine. I believe
this is backed up by the pings seen in mom.log
Though I can see the following in vdsm.log... [vds] recovery:
waiting for storage pool to go up (clientIF:569)
So I wonder if this is blocking the engine bringing the host up.
The host is running local storage, which I believe is a pretty
recent addition to ovirt. So I could see how trying to run an engine
VM on a host's local storage might cause weird issues.
Maybe I lost a piece here.
Are you trying to migrate an old 3.6 all-in-one setup (where
ovirt-engine - the manager - and vdsm - the agent on the host are
running on the same host) to hosted-engine in a single step?
In that case it will not work for sure since when you will power-down
the old engine machine you will also power-down your old host and so the
new engine running on the VM is not able to contact the host since the
old host is down.
In hosted-engine idea, the engine runs on a VM running on the host that
its managing.
In that case probably the most effective way is to:
within your old engine:
- create a datacenter with shared storage (please avoid using NFS in
loopback)
- add your new hosts there
- migrate all of your VMs to the new dataceter
- only now you can migrate to hosted-engine
Thank you for the further reply. Those links appear to work for me now
so perhaps it was a temporary failure.
At the moment I am running engine 4.1.4.2-1.el7 on CentOS 7.3.1611
It's on a bare-metal machine, the same machine is acting as the host,
and all accessing local storage (ISO domain and a VM datastore).
So it's an all-in-one setup but of my own installation, not using any
previous all-in-one installation scripts.
I basically installed ovirt engine on a machine, then deployed the host
onto the same machine, then setup local datastores.
Is this a possible (though not necessarily supported) migration path in
any way?
It sounds like shared storage is basically a prerequisite for hosted
engine after all - not running it off a single host's local storage.
Thanks
I realise that there won't be HA with this setup, until I create my
second host and configure HA on the VM.
If I am unable to migrate from bare-metal -> engine VM then it
doesn't give me any confidence that I would be able to restore a
setup from a backup onto a bare-metal host and recover host state.
So is the only supported method of migrating from bare-metal engine
to hosted engine by...
1) Migrating to the appliance
2) Using a new host to migrate to VM
3) Using shared storage between hosts
Thanks, Ben
The only detail is that hosted-engine-setup will try to add
the host where you are running it to the engine and so you
have to manually remove it just after the restore in order
to avoid a failure there.
Can anyone describe that process in a bit more detail?
Is it possible to perform any part of that process
manually?
I'm planning to expand my lab and dev environments so
for me it's
important to discover the following...
- That I'm able to reverse the process back to
bare-metal engine if
I ever need/want to
- That I can setup a new VM or host with nothing more
than an
engine-backup but still be able to regain control of
exiting hosts
and VMs within the cluster
My main concern after my basic attempt at a
"restore/migration"
above is that I might not be able to re-import/sync an
existing host
after I have restored engine from a backup.
I have been able to export VMs to storage, remove them
from ovirt,
re-install engine and restore, then import VMs from the
export
domain. That all worked fine. But it involved shutting
down all VMs
and removing their definitions from the environment.
Are there any pre-requisites to being able to re-import
an existing
running host (and VMs), such as placing ALL hosts into
maintenance
mode and shutting down any VMs first?
Any insight into host recovery/import/sync processes
and steps will
be greatly appreciated.
Best regards
Ben
_______________________________________________
Users mailing list
Users@ovirt.org <mailto:Users@ovirt.org>
<mailto:Users@ovirt.org <mailto:Users@ovirt.org>>
http://lists.ovirt.org/mailman/listinfo/users
<http://lists.ovirt.org/mailman/listinfo/users>
<http://lists.ovirt.org/mailman/listinfo/users
<http://lists.ovirt.org/mailman/listinfo/users>>
_______________________________________________
Users mailing list
Users@ovirt.org <mailto:Users@ovirt.org>
http://lists.ovirt.org/mailman/listinfo/users
<http://lists.ovirt.org/mailman/listinfo/users>
_______________________________________________
Users mailing list
Users@ovirt.org <mailto:Users@ovirt.org>
http://lists.ovirt.org/mailman/listinfo/users
<http://lists.ovirt.org/mailman/listinfo/users>
_______________________________________________
Users mailing list
Users@ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
