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On 18/09/15 07:30, Luca Bertoncello wrote:
Hi all,
thank you very much for your answers.
So:
1)Of course, we have UPS. More than one, in our server room, and of
course they will send an advice to the host if they are on battery
Good.
2)My question was: what can I do, so that in case of Kernel Panic or
similar, the VM will be migrated (live or not) to another host?
You would make the VMs HA and acquire a fencing solution.
3)Id like to have a shutdown-script on the host that put the host in
Maintenance and wait until its done, so that I can just shutdown or
reboot it without any other action. Is it possible? It would help to
manage the power failure, too, assuming that other hosts have better
UPS (it can be possible
)
You could probably use the REST API on the Ovirt Engine for that.But it
might be better to have a highly available machine (VM or not) running
something like Nagios or Icinga which would perform the monitoring of
your hosts and connect to the REST API to perform maintenance and
shutdown. You might also consider a UPS service like NUT (unless you're
already doing it).
Cheers
Alex
Thanks a lot
Mit freundlichen Grüßen
Luca Bertoncello
--
Besuchen Sie unsere Webauftritte:
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Luca Bertoncello
Administrator
Telefon:
+49 351 21 30 38 0
Fax:
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queo GmbH
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01159 Dresden
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USt-IdNr.: DE234220077
*From:*users-bounces@ovirt.org [mailto:users-bounces@ovirt.org] *On
Behalf Of *matthew lagoe
*Sent:* Thursday, September 17, 2015 9:56 PM
*To:* 'Alex Crow'; 'Yaniv Kaul'
*Cc:* users(a)ovirt.org
*Subject:* Re: [ovirt-users] Automatically migrate VM between hosts in
the same cluster
There are PDUs that you can monitor power draw per port and that
would kind of tell you if a PSU failed as the load would be 0
*From:*users-bounces@ovirt.org <mailto:users-bounces@ovirt.org>
[mailto:users-bounces@ovirt.org] *On Behalf Of *Alex Crow
*Sent:* Thursday, September 17, 2015 12:31 PM
*To:* Yaniv Kaul <ykaul(a)redhat.com <mailto:ykaul@redhat.com>>
*Cc:* users(a)ovirt.org <mailto:users@ovirt.org>
*Subject:* Re: [ovirt-users] Automatically migrate VM between hosts in
the same cluster
I don't really think this is practical:
- If the PSU failed, your UPS could alert you. If you have one...
If you have only one PSU in a host, a UPS is not going to stop you
losing all the VMs on that host. OK, if you had N+1 PSUs, you may be
able to monitor for this (IPMI/LOM/DRAC etc)and use the API to put a
host into maintenance. Also a lot of people rely on low-cost white-box
servers and decide that it's OK if a single PSU in a host dies, as,
well, we have HA to start on other hosts. If they have N+1 PSUs in the
hosts do they really have to migrate everything off? Swings and
roundabouts really.
I'm also not sure I've seen any practical DC setups where a UPS can
monitor the load for every single attached physical machine and figure
out that one of the redundant PSUs in it has failed - I'd love to know
if there are as that would be really cool.
- If the machine is going down in an ordinary flow, surely it can
be done.
Isn't that what "Maintenance mode" is for?
Â
Even if it was a network failure and the host was still up,
how would you live migrate a VM from a host you can't even
talk to?
It could be suspended to disk (local) - if the disk is available.
Then the decision if it is to be resumed from local disk or not
(as it might be HA'ed and is running elsewhere) need to be taken
later, of course.
Yes, but that's not even remotely possible with Ovirt right now. I was
trying to be practical as the OP has only just started using Ovirt and
I think it might be a bit much to ask him to start coding up what he'd
like.
Â
The only way you could do it was if you somehow magically knew
far enough in advance that the host was about to fail (!) and
that gave enough time to migrate the machines off. But how
would you ever know that "machine
quux.bar.net
<
http://quux.bar.net> is going to fail in 7 minutes"?
I completely agree there are situations in which you can't foresee
the failure.Â
But in many, you can. In those cases, it makes sense for the host
to self-initiate 'move to maintenance' mode. The policy of what to
do when 'self-moving-to-maintenance-mode' could be pre-fetched
from the engine.
Y.
Hmm, I would love that to be true. But I've seen so many so called
"corner-cases" that I now think the failure area in a datacenter is a
fractal with infinite corners. Yes, you could monitor SMART on local
drives, pick up uncorrected ECC errors, use "sensors" to check for
sagging voltages or high temps, but I don't think you can ever hope to
catch everything, and you could end up doing a migration "storm" for .
I've had more than enough of "Enterprise Spec" switches suddenly going
nuts and spamming corrupt MACs all over the LAN to know you can't ever
account for everything.
I think it's better to adopt the model of redundancy in software and
services, so no-one even notices if a VM host goes away, there's
always something else to take up the slack. Just like the origins of
the Internet - the network should be dumb and the applications should
cope with it! Any infrastructure that can't cope with the loss of a
few VMs for a few minutes probably needs a refresh.
Cheers
Alex
.
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Users mailing list
Users(a)ovirt.org
http://lists.ovirt.org/mailman/listinfo/users
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<div class="moz-cite-prefix">On 18/09/15 07:30, Luca Bertoncello
wrote:<br>
</div>
<blockquote
cite="mid:DC8168E813106D47ADB2BA2C8A46E9FF327AB9C13C@sphinx.queo.local"
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<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi
all,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US">thank you very much for your
answers.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US">So:<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><!--[if
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style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US"><span
style="mso-list:Ignore">1)<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US">Of course, we have UPS. More than one, in our
server room, and of course they will send an advice to the
host if they are on battery</span></p>
</div>
</blockquote>
<br>
Good.<br>
<br>
<blockquote
cite="mid:DC8168E813106D47ADB2BA2C8A46E9FF327AB9C13C@sphinx.queo.local"
type="cite">
<div class="WordSection1">
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US"><o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><!--[if
!supportLists]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US"><span
style="mso-list:Ignore">2)<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US">My question was: what can I do, so that in
case of Kernel Panic or similar, the VM will be migrated
(live or not) to another host?</span></p>
</div>
</blockquote>
<br>
You would make the VMs HA and acquire a fencing solution.<br>
<br>
<blockquote
cite="mid:DC8168E813106D47ADB2BA2C8A46E9FF327AB9C13C@sphinx.queo.local"
type="cite">
<div class="WordSection1">
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US"><o:p></o:p></span></p>
<p class="MsoListParagraph"
style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><!--[if
!supportLists]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US"><span
style="mso-list:Ignore">3)<span
style="font:7.0pt "Times New Roman"">
</span></span></span><!--[endif]--><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US">Id like to have a shutdown-script on the host
that put the host in Maintenance and wait until its done,
so that I can just shutdown or reboot it without any other
action. Is it possible? It would help to manage the power
failure, too, assuming that other hosts have better UPS (it
can be possible
)</span></p>
</div>
</blockquote>
<br>
You could probably use the REST API on the Ovirt Engine for that.But
it might be better to have a highly available machine (VM or not)
running something like Nagios or Icinga which would perform the
monitoring of your hosts and connect to the REST API to perform
maintenance and shutdown. You might also consider a UPS service like
NUT (unless you're already doing it).<br>
<br>
Cheers<br>
<br>
Alex<br>
<br>
<blockquote
cite="mid:DC8168E813106D47ADB2BA2C8A46E9FF327AB9C13C@sphinx.queo.local"
type="cite">
<div class="WordSection1">
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lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US">Thanks a
lot<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"
style="margin-bottom:12.0pt"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Mit
freundlichen Grüßen<br>
<br>
Luca Bertoncello<br>
<br>
-- <br>
Besuchen Sie unsere
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<p class="MsoNormal"><b><span
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style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">
<a class="moz-txt-link-abbreviated"
href="mailto:users-bounces@ovirt.org">users-bounces@ovirt.org</a>
[<a class="moz-txt-link-freetext"
href="mailto:users-bounces@ovirt.org">mailto:users-bounces@ovirt.org</a>]
<b>On Behalf Of </b>matthew
lagoe<br>
<b>Sent:</b> Thursday, September 17, 2015 9:56 PM<br>
<b>To:</b> 'Alex Crow'; 'Yaniv
Kaul'<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated"
href="mailto:users@ovirt.org">users@ovirt.org</a><br>
<b>Subject:</b> Re: [ovirt-users] Automatically
migrate VM between hosts in the same
cluster<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US">There are PDUs that you can monitor power
draw per port and that would kind of tell you if a PSU
failed as the load would be 0<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"
lang="EN-US"><o:p> </o:p></span></p>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:windowtext"
lang="EN-US">From:</span></b><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:windowtext"
lang="EN-US"> <a moz-do-not-send="true"
href="mailto:users-bounces@ovirt.org">users-bounces@ovirt.org</a>
[<a moz-do-not-send="true"
href="mailto:users-bounces@ovirt.org">mailto:users-bounces@ovirt.org</a>]
<b>On Behalf Of </b>Alex Crow<br>
<b>Sent:</b> Thursday, September 17, 2015 12:31
PM<br>
<b>To:</b> Yaniv Kaul <<a
moz-do-not-send="true"
href="mailto:ykaul@redhat.com">ykaul@redhat.com</a>><br>
<b>Cc:</b> <a moz-do-not-send="true"
href="mailto:users@ovirt.org">users@ovirt.org</a><br>
<b>Subject:</b> Re: [ovirt-users] Automatically
migrate VM between hosts in the same
cluster<o:p></o:p></span></p>
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<p class="MsoNormal"><span
lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"
style="margin-bottom:12.0pt"><span
lang="EN-US">I don't really think this is
practical:<br>
<br>
<o:p></o:p></span></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
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<p class="MsoNormal"><span
lang="EN-US">- If the PSU
failed, your UPS could alert you. If you have
one...<o:p></o:p></span></p>
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</blockquote>
<p class="MsoNormal"
style="margin-bottom:12.0pt"><span
lang="EN-US"><br>
If you have only one PSU in a host, a UPS is not going to
stop you losing all the VMs on that host. OK, if you had
N+1 PSUs, you may be able to monitor for this
(IPMI/LOM/DRAC etc)and use the API to put a host into
maintenance. Also a lot of people rely on low-cost
white-box servers and decide that it's OK if a single PSU
in a host dies, as, well, we have HA to start on other
hosts. If they have N+1 PSUs in the hosts do they really
have to migrate everything off? Swings and roundabouts
really.<br>
<br>
I'm also not sure I've seen any practical DC setups where
a UPS can monitor the load for every single attached
physical machine and figure out that one of the redundant
PSUs in it has failed - I'd love to know if there are as
that would be really cool.<br>
<br>
<o:p></o:p></span></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
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<p class="MsoNormal"><span
lang="EN-US">- If the
machine is going down in an ordinary flow,
surely it can be done.
<o:p></o:p></span></p>
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</blockquote>
<p class="MsoNormal"
style="margin-bottom:12.0pt"><span
lang="EN-US"><br>
Isn't that what "Maintenance mode" is for?<br>
<br>
<o:p></o:p></span></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
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<p class="MsoNormal"><span
lang="EN-US">Â <o:p></o:p></span></p>
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6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt">
<p class="MsoNormal"><span
lang="EN-US"><br>
Even if it was a network failure and the host
was still up, how would you live migrate a VM
from a host you can't even talk
to?<o:p></o:p></span></p>
</blockquote>
<div>
<p class="MsoNormal"><span
lang="EN-US"><o:p> </o:p></span></p>
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<div>
<p class="MsoNormal"><span
lang="EN-US">It could be
suspended to disk (local) - if the disk is
available.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
lang="EN-US">Then the
decision if it is to be resumed from local disk
or not (as it might be HA'ed and is running
elsewhere) need to be taken later, of
course.<o:p></o:p></span></p>
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<p class="MsoNormal"
style="margin-bottom:12.0pt"><span
lang="EN-US"><br>
Yes, but that's not even remotely possible with Ovirt
right now. I was trying to be practical as the OP has only
just started using Ovirt and I think it might be a bit
much to ask him to start coding up what he'd like.<br>
<br>
<o:p></o:p></span></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
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<div>
<div>
<div>
<p class="MsoNormal"><span
lang="EN-US"><o:p> </o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
lang="EN-US">Â <o:p></o:p></span></p>
</div>
<blockquote style="border:none;border-left:solid
#CCCCCC 1.0pt;padding:0cm 0cm 0cm
6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0cm;margin-bottom:5.0pt">
<p class="MsoNormal"><span
lang="EN-US"><br>
The only way you could do it was if you somehow
magically knew far enough in advance that the
host was about to fail (!) and that gave enough
time to migrate the machines off. But how would
you ever know that "machine <a
moz-do-not-send="true"
href="http://quux.bar.net"
target="_blank">quux.bar.net</a>
is going to fail in 7
minutes"?<o:p></o:p></span></p>
</blockquote>
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<p class="MsoNormal"><span
lang="EN-US"><o:p> </o:p></span></p>
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<div>
<p class="MsoNormal"><span
lang="EN-US">I completely
agree there are situations in which you can't
foresee the
failure. <o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
lang="EN-US">But in many,
you can. In those cases, it makes sense for the
host to self-initiate 'move to maintenance'
mode. The policy of what to do when
'self-moving-to-maintenance-mode' could be
pre-fetched from the
engine.<o:p></o:p></span></p>
</div>
<div>
<p class="MsoNormal"><span
lang="EN-US">Y.<o:p></o:p></span></p>
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</blockquote>
<p class="MsoNormal"><span
lang="EN-US"><br>
Hmm, I would love that to be true. But I've seen so many
so called "corner-cases" that I now think the failure area
in a datacenter is a fractal with infinite corners. Yes,
you could monitor SMART on local drives, pick up
uncorrected ECC errors, use "sensors" to check for sagging
voltages or high temps, but I don't think you can ever
hope to catch everything, and you could end up doing a
migration "storm" for . I've had more than enough of
"Enterprise Spec" switches suddenly going nuts and
spamming corrupt MACs all over the LAN to know you can't
ever account for everything.<br>
<br>
I think it's better to adopt the model of redundancy in
software and services, so no-one even notices if a VM host
goes away, there's always something else to take up the
slack. Just like the origins of the Internet - the network
should be dumb and the applications should cope with it!
Any infrastructure that can't cope with the loss of a few
VMs for a few minutes probably needs a refresh.<br>
<br>
Cheers<br>
<br>
Alex<br>
<br>
<br>
<br>
<br>
<br>
. <o:p></o:p></span></p>
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