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<p>Yes, by determining the size of the attachments list.<br>
</p>
<p>CLI: <i>openstack volume show </i>displays attachment details.
<br>
</p>
<p>API: The response for the <a
href="https://developer.openstack.org/api-ref/block-storage/v3/index.html?expanded=show-a-volume-s-details-detail#show-a-volume-s-details">volume
details API</a> contains an <i>attachments </i>parameter.</p>
<p>On 7/2/2019 1:14 PM, RAI, SNEHA wrote:<br>
</p>
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<p class="MsoNormal"><span style="color:#1F497D">Hi All,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Is there a way
to find in cinder how many instances are attached to a
volume?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Thanks &
Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Sneha Rai<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b>From:</b> RAI, SNEHA <br>
<b>Sent:</b> Monday, July 1, 2019 5:26 PM<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:openstack-dev@lists.openstack.org">openstack-dev@lists.openstack.org</a><br>
<b>Subject:</b> HPE 3PAR Cinder driver-Multiattach: Fails
to detach second instance from volume<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi Team,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">There is a bug on 3PAR Cinder driver <a
href="https://bugs.launchpad.net/cinder/+bug/1834660"
moz-do-not-send="true">
https://bugs.launchpad.net/cinder/+bug/1834660</a>.<o:p></o:p></p>
<p class="MsoNormal">I am able to attach multiple instances to
3PAR volume but only the first instance gets detached
successfully.<o:p></o:p></p>
<p class="MsoNormal">For the second instance, volume goes into
detaching status due to “Host does not exist” error.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">What is happening here is, the first detach
call invokes <span
style="font-size:9.0pt;font-family:Consolas;color:#333333;background:white">_delete_3par_host()
</span>which removes the compute host entry from 3PAR which
ideally should be done only when the last instance is to be
detached.<o:p></o:p></p>
<p class="MsoNormal">It would be great if someone could help me
understand if this needs to be handled in driver code or nova
would internally take care of it.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Code changes done to support multiattach-<a
href="https://review.opendev.org/#/c/659443"
moz-do-not-send="true">https://review.opendev.org/#/c/659443</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks & Regards,<o:p></o:p></p>
<p class="MsoNormal">Sneha Rai<o:p></o:p></p>
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