11:41 a.m.
Hi,
please consider this bugreport:
https://bugzilla.redhat.com/show_bug.cgi?id=1111520
it is about the default fencing behaviour of ovirt
in the special case of a single node cluster when
a logical network marked as "required" is not available
on the single host in the cluster.
the default behaviour is, to shutdown all vms.
You can find reasoning in the BZ why this is, well,
"bad", to say the least.
Thanks in advance.
--
Mit freundlichen Grüßen / Regards
Sven Kieske
Systemadministrator
Mittwald CM Service GmbH & Co. KG
Königsberger Straße 6
32339 Espelkamp
T: +49-5772-293-100
F: +49-5772-293-333
https://www.mittwald.de
Geschäftsführer: Robert Meyer
St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen
Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen
12:34 p.m.
New subject: [ovirt-devel] design flaw in ovirt
On Fri, Jun 20, 2014 at 08:41:21AM +0000, Sven Kieske wrote:
Hi,
please consider this bugreport:
https://bugzilla.redhat.com/show_bug.cgi?id=1111520
it is about the default fencing behaviour of ovirt
in the special case of a single node cluster when
a logical network marked as "required" is not available
on the single host in the cluster.
the default behaviour is, to shutdown all vms.
You can find reasoning in the BZ why this is, well,
"bad", to say the least.
I do not quite understand the problem you describe.
Does the problem go away if you set your network to "non-required"? If
your VM's app does not strictly require unintermitant networking, just
set the networ to non-required. Flipping the default of requiredness
can be considered only for 4.0 ("required" was our default since ever,
other users' scripts may depend on that).
Could you attach Vdsm and Engine logs to the bug? How was the host
fenced?
Dan.
12:53 p.m.
New subject: [ovirt-devel] design flaw in ovirt
Am 20.06.2014 11:34, schrieb Dan Kenigsberg:
I do not quite understand the problem you describe.
See below, I hope this clears some things up.
Does the problem go away if you set your network to
"non-required"? If
your VM's app does not strictly require unintermitant networking, just
set the networ to non-required. Flipping the default of requiredness
can be considered only for 4.0 ("required" was our default since ever,
other users' scripts may depend on that).
I know you can't simply switch the default behaviour, and yes, at least
according to the documentation setting the network to "non-required"
should mitigate the issue.
however, the default is, to set every network as "required" without
indicating this to the user in the first place (and the consequences
of this not advertised behaviour).
Could you attach Vdsm and Engine logs to the bug? How was the host
fenced?
the host was not fenced, the vms where fenced.
here is a link to the documentation which should explain what I mean:
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Vir...
this is about a single host in a cluster - ovirt can't even fence
single hosts in a single cluster yet, see my other bug report for this:
https://bugzilla.redhat.com/show_bug.cgi?id=1054778
I could provide logs if they are really necessary, but I doubt they are.
This is documented behaviour, but it is poorly designed, as described
in the BZ.
The fencing mechanism is really buggy / not helpful, see
also this (not really related) bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1090799
--
Mit freundlichen Grüßen / Regards
Sven Kieske
Systemadministrator
Mittwald CM Service GmbH & Co. KG
Königsberger Straße 6
32339 Espelkamp
T: +49-5772-293-100
F: +49-5772-293-333
https://www.mittwald.de
Geschäftsführer: Robert Meyer
St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen
Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen
3:19 p.m.
New subject: [ovirt-devel] design flaw in ovirt
On Fri, Jun 20, 2014 at 09:53:24AM +0000, Sven Kieske wrote:
Am 20.06.2014 11:34, schrieb Dan Kenigsberg:
>
> I do not quite understand the problem you describe.
See below, I hope this clears some things up.
> Does the problem go away if you set your network to "non-required"? If
> your VM's app does not strictly require unintermitant networking, just
> set the networ to non-required. Flipping the default of requiredness
> can be considered only for 4.0 ("required" was our default since ever,
> other users' scripts may depend on that).
I know you can't simply switch the default behaviour, and yes, at least
according to the documentation setting the network to "non-required"
should mitigate the issue.
however, the default is, to set every network as "required" without
indicating this to the user in the first place (and the consequences
of this not advertised behaviour).
> Could you attach Vdsm and Engine logs to the bug? How was the host
> fenced?
the host was not fenced, the vms where fenced.
here is a link to the documentation which should explain what I mean:
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Vir...
Are you refering to the paragraph: "When a required network becomes
non-operational, the virtual machines running on the network are fenced
and migrated to another host. This is beneficial if you have machines
running mission critical workloads."?
this is about a single host in a cluster - ovirt can't even fence
single hosts in a single cluster yet, see my other bug report for this:
https://bugzilla.redhat.com/show_bug.cgi?id=1054778
I could provide logs if they are really necessary, but I doubt they are.
This is documented behaviour, but it is poorly designed, as described
in the BZ.
Apparently, I am not familiar enough with Engine's fencing logic; logs
may help me understand the issue, for me they are necessary is this
case. In particular, I'd like to see with my own eyes whether the VMs
where explicitly destroyed by Engine. Migrating VMs to an operational
destination makes a lot of sense. Destroying a running VM in attempt
to recuperate of a host networking issue is extraordinary (and as such,
requires exraordinary evidence).
The fencing mechanism is really buggy / not helpful, see
I vote for "buggy/imperfect". I am aware of mission-critical VMs that
are kept highly-available due to it.
also this (not really related) bug:
https://bugzilla.redhat.com/show_bug.cgi?id=1090799
Regards,
Dan.
3:52 p.m.
New subject: [ovirt-devel] design flaw in ovirt
Am 20.06.2014 14:19, schrieb Dan Kenigsberg:
> the host was not fenced, the vms where fenced.
>
> here is a link to the documentation which should explain what I mean:
>
>
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Vir...
Are you refering to the paragraph: "When a required network becomes
non-operational, the virtual machines running on the network are fenced
and migrated to another host. This is beneficial if you have machines
running mission critical workloads."?
yes
>
> this is about a single host in a cluster - ovirt can't even fence
> single hosts in a single cluster yet, see my other bug report for this:
> https://bugzilla.redhat.com/show_bug.cgi?id=1054778
>
> I could provide logs if they are really necessary, but I doubt they are.
> This is documented behaviour, but it is poorly designed, as described
> in the BZ.
Apparently, I am not familiar enough with Engine's fencing logic; logs
may help me understand the issue, for me they are necessary is this
case. In particular, I'd like to see with my own eyes whether the VMs
where explicitly destroyed by Engine. Migrating VMs to an operational
destination makes a lot of sense. Destroying a running VM in attempt
to recuperate of a host networking issue is extraordinary (and as such,
requires exraordinary evidence).
I might be able to attach some logs later.
--
Mit freundlichen Grüßen / Regards
Sven Kieske
Systemadministrator
Mittwald CM Service GmbH & Co. KG
Königsberger Straße 6
32339 Espelkamp
T: +49-5772-293-100
F: +49-5772-293-333
https://www.mittwald.de
Geschäftsführer: Robert Meyer
St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen
Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen
4:32 p.m.
New subject: [ovirt-devel] design flaw in ovirt
On 06/20/2014 02:52 PM, Sven Kieske wrote:
Am 20.06.2014 14:19, schrieb Dan Kenigsberg:
>> the host was not fenced, the vms where fenced.
>>
>> here is a link to the documentation which should explain what I mean:
>>
>>
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Vir...
> Are you refering to the paragraph: "When a required network becomes
> non-operational, the virtual machines running on the network are fenced
> and migrated to another host. This is beneficial if you have machines
> running mission critical workloads."?
yes
Isn't that section referring to HA VMs?
>> this is about a single host in a cluster - ovirt can't even fence
>> single hosts in a single cluster yet, see my other bug report for this:
>> https://bugzilla.redhat.com/show_bug.cgi?id=1054778
>>
>> I could provide logs if they are really necessary, but I doubt they are.
>> This is documented behaviour, but it is poorly designed, as described
>> in the BZ.
> Apparently, I am not familiar enough with Engine's fencing logic; logs
> may help me understand the issue, for me they are necessary is this
> case. In particular, I'd like to see with my own eyes whether the VMs
> where explicitly destroyed by Engine. Migrating VMs to an operational
> destination makes a lot of sense. Destroying a running VM in attempt
> to recuperate of a host networking issue is extraordinary (and as such,
> requires exraordinary evidence).
I might be able to attach some logs later.
--
Regards,
Vinzenz Feenstra | Senior Software Engineer
RedHat Engineering Virtualization R & D
Phone: +420 532 294 625
IRC: vfeenstr or evilissimo
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4:42 p.m.
New subject: [ovirt-devel] design flaw in ovirt
Am 20.06.2014 15:32, schrieb Vinzenz Feenstra:
Isn't that section referring to HA VMs?
No.
--
Mit freundlichen Grüßen / Regards
Sven Kieske
Systemadministrator
Mittwald CM Service GmbH & Co. KG
Königsberger Straße 6
32339 Espelkamp
T: +49-5772-293-100
F: +49-5772-293-333
https://www.mittwald.de
Geschäftsführer: Robert Meyer
St.Nr.: 331/5721/1033, USt-IdNr.: DE814773217, HRA 6640, AG Bad Oeynhausen
Komplementärin: Robert Meyer Verwaltungs GmbH, HRB 13260, AG Bad Oeynhausen
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6 comments
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participants (3)
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Vinzenz Feenstra