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On 08/27/2015 10:43 AM, Ivan Kolodyazhny wrote:<br>
<blockquote
cite="mid:CAGocpaGizCGO2gr=XBvT62k1xDRaNqi4JNbn682P=_vWRJT+uA@mail.gmail.com"
type="cite">
<div dir="ltr">Hi,
<div><br>
</div>
<div>Looks like we need to be able to set AZ per backend. What
do you think about such option?<br>
</div>
</div>
</blockquote>
<br>
I dislike such an option.<br>
<br>
The whole premise behind an AZ is that it's a failure domain. The
node running the cinder services is in exactly one such failure
domain. If you have 2 backends in 2 different AZs, then the cinder
services managing those backends should be running on nodes that are
also in those AZs. If you do it any other way then you create a
situation where a failure in one AZ causes loss of services in a
different AZ, which is exactly what the AZ feature is trying to
avoid.<br>
<br>
If you do the correct thing and run cinder services on nodes in the
AZs that they're managing then you will never have a problem with
the one-AZ-per-cinder.conf design we have today.<br>
<br>
-Ben<br>
<br>
<br>
<blockquote
cite="mid:CAGocpaGizCGO2gr=XBvT62k1xDRaNqi4JNbn682P=_vWRJT+uA@mail.gmail.com"
type="cite">
<div dir="ltr">
<div>
<div class="gmail_extra"><br clear="all">
<div>
<div class="gmail_signature">Regards,<br>
Ivan Kolodyazhny</div>
</div>
<br>
<div class="gmail_quote">On Mon, Aug 10, 2015 at 7:07 PM,
John Griffith <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:john.griffith8@gmail.com" target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:john.griffith8@gmail.com">john.griffith8@gmail.com</a></a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">
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<div class="h5">
<div style="font-family:monospace,monospace"><br>
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<div class="gmail_extra"><br>
<div class="gmail_quote">On Mon, Aug 10, 2015 at
9:24 AM, Dulko, Michal <span dir="ltr"><<a
moz-do-not-send="true"
href="mailto:michal.dulko@intel.com"
target="_blank"><a class="moz-txt-link-abbreviated" href="mailto:michal.dulko@intel.com">michal.dulko@intel.com</a></a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="margin:0 0 0 .8ex;border-left:1px
#ccc solid;padding-left:1ex">Hi,<br>
<br>
In Kilo cycle [1] was merged. It started
passing AZ of a booted VM to Cinder to make
volumes appear in the same AZ as VM. This is
certainly a good approach, but I wonder how
to deal with an use case when administrator
cares about AZ of a compute node of the VM,
but wants to ignore AZ of volume. Such case
would be when fault tolerance of storage is
maintained on another level - for example
using Ceph replication and failure domains.<br>
<br>
Normally I would simply disable
AvailabilityZoneFilter in cinder.conf, but
it turns out cinder-api validates if
availability zone is correct [2]. This means
that if Cinder has no AZs configured all
requests from Nova will fail on an API
level.<br>
<br>
Configuring fake AZs in Cinder is also
problematic, because AZ cannot be configured
on a per-backend manner. I can only
configure it per c-vol node, so I would need
N extra nodes running c-vol, where N is
number of AZs to achieve that.<br>
<br>
Is there any solution to satisfy such use
case?<br>
<br>
[1] <a moz-do-not-send="true"
href="https://review.openstack.org/#/c/157041"
rel="noreferrer" target="_blank">https://review.openstack.org/#/c/157041</a><br>
[2] <a moz-do-not-send="true"
href="https://github.com/openstack/cinder/blob/master/cinder/volume/flows/api/create_volume.py#L279-L282"
rel="noreferrer" target="_blank">https://github.com/openstack/cinder/blob/master/cinder/volume/flows/api/create_volume.py#L279-L282</a><br>
<br>
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<br>
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<div class="gmail_extra">
<div style="font-family:monospace,monospace">Seems
like we could introduce the capability in cinder
to ignore that if it's desired? It would probably
be worth looking on the Cinder side at being able
to configure multiple AZ's for a volume (perhaps
even an aggregate Zone just for Cinder). That way
we still honor the setting but provide a way to
get around it for those that know what they're
doing.</div>
<span class="HOEnZb"><font color="#888888">
<div style="font-family:monospace,monospace"><br>
</div>
<div style="font-family:monospace,monospace">John</div>
<br>
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