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<p style="margin: 0 0 1em 0; color: black;">Originally the NFS driver did
support snapshots, but it was implemented by just 'cp'ing the file
containing the raw bits. This works fine (if inefficiently) for unattached
volumes, but if you do this on an attached volume the snapshot won't be
crash consistent at all.</p>
<p style="margin: 0 0 1em 0; color: black;">It was decided that we could do
better for attached volumes by switching to qcow2 and relying on nova to
perform the snapshots. Based on this, the bad snapshot implementation was
removed.</p>
<p style="margin: 0 0 1em 0; color: black;">However, for a variety of
reasons the nova-assisted snapshot implementation has remained unmerged for
2+ years and the NFS driver has been an exception to the rules for that
whole time.</p>
<p style="margin: 0 0 1em 0; color: black;">I would like to see that
exception end in the near future with either the removal of the driver or
the completion of the Nova-assisted snapshot implementation, and it doesn't
really matter to me which.</p>
<p style="margin: 0 0 1em 0; color: black;">There is a 3rd alternative
which would be to modify the NFS driver to require a specific filesystem
that supports snapshots (there are a few choices here, but definitely NOT
ext4). Unfortunately those of us who work for storage vendors aren't
motivated to make such a modification because it would be effectively
creating more competition for ourselves. The only way this could happen is
if someone not working for a storage vendor takes this on.</p>
<p style="margin: 0 0 1em 0; color: black;">-Ben</p>
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<p
style="color: black; font-size: 10pt; font-family: Arial, sans-serif; margin: 10pt 0;">On
August 25, 2016 10:39:35 AM Erlon Cruz <sombrafam@gmail.com> wrote:</p>
<blockquote type="cite" class="gmail_quote"
style="margin: 0 0 0 0.75ex; border-left: 1px solid #808080; padding-left: 0.75ex;">
<div dir="ltr">Hi Jordan, Slade,<div><br></div><div>Currently NFS driver
does not support cloning neither snapshots (which are the base for
implementing cloning). AFAIC, the NFS driver was in Cinder before the
minimum requirements being discussed and set, so, it just stood there with
the features it already supported.</div><div><br></div><div>There is
currently this job
'gate-tempest-dsvm-full-devstack-plugin-nfs-nv'[1] that by the way
are failing in the same test you mentioned tough passing the snapshot tests
(not shure how the configuration is doing that) and a work[2] in progress
to support the snapshot feature.</div><div><br></div><div>So, Jordan, I
think its OK to allow tempest to skip this tests, provided that at least in
the NFS driver, tempest isn't being an enforcement to Cinder minimum
features
requirements.</div><div><br></div><div>Erlon<br></div><div><br></div><div><br></div><div>[1]
<a
href="http://logs.openstack.org/86/147186/25/experimental/gate-tempest-dsvm-full-devstack-plugin-nfs-nv/b149960/">http://logs.openstack.org/86/147186/25/experimental/gate-tempest-dsvm-full-devstack-plugin-nfs-nv/b149960/</a></div><div>[2]
<a
href="https://review.openstack.org/#/c/147186/">https://review.openstack.org/#/c/147186/</a> </div></div><div
class="gmail_extra"><br><div class="gmail_quote">On Wed, Aug 24, 2016 at
6:34 PM, Jordan Pittier <span dir="ltr"><<a
href="mailto:jordan.pittier@scality.com"
target="_blank">jordan.pittier@scality.com</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"><div class="gmail_extra"><br><div class="gmail_quote"><div><div
class="h5">On Wed, Aug 24, 2016 at 6:06 PM, Slade Baumann <span
dir="ltr"><<a href="mailto:baumann@us.ibm.com"
target="_blank">baumann@us.ibm.com</a>></span> wrote:<br><blockquote
class="gmail_quote"
style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><font
face="Verdana,Arial,Helvetica,sans-serif" size="2">I am attempting to
disable clone tests in tempest as they aren't<br>functioning in NFS.
But the tests test_volumes_clone.py and<br>test_volumes_clone_negative.py
don't have the "clone" feature<br>toggle in them. I thought
it obvious that if clone is disabled<br>in tempest, the tests that simply
clone should be disabled.<br><br>So I put up a bug and fix for it, but have
been talking with<br>Jordan Pittier and he suggested I come to the mailing
list to<br>get this figured out. <br><br>I'm not asking for reviews,
unless you want to give them.<br>I'm simply asking if this is the right
way to go about this<br>or if there is something else I need to do to get
this into<br>Tempest.<br><br>Here are the bug and fix:<br><a
href="https://bugs.launchpad.net/tempest/+bug/1615770"
target="_blank">https://bugs.launchpad.net/tem<wbr>pest/+bug/1615770</a><br><a
href="https://review.openstack.org/#/c/358813/"
target="_blank">https://review.openstack.org/#<wbr>/c/358813/</a><br><br>I
would appreciate any suggestion or direction in this problem.<br><br>For
extra reference, the clone toggle flag was added here:<br><a
href="https://bugs.launchpad.net/tempest/+bug/1488274"
target="_blank">https://bugs.launchpad.net/tem<wbr>pest/+bug/1488274</a></font><br>
<br></blockquote></div></div><div>Hi, </div><div>Thanks for starting this
thread. My point about this patch is, as "volume clone" is part
of the core requirements [1] every Cinder drive must support, I don't
see a need for a feature flag. The feature flag already exists, but that
doesn't mean we should encourage its
usage.</div><div><br></div><div>Now, if this really helps the NFS driver
(although I don"t know why we couldn't support clone with NFS)...
I don't have a strong opinion on this patch.</div><div><br></div><div>I
-1ed the patch for consistency: I agree that there should be a minimum set
of features expected from a Cinder driver.</div><div><br></div><div>[1] <a
href="http://docs.openstack.org/developer/cinder/devref/drivers.html#core-functionality"
target="_blank">http://docs.openstack.org/<wbr>developer/cinder/devref/<wbr>drivers.html#core-<wbr>functionality</a></div><div><br></div><div>Cheers,</div><div>Jordan </div></div></div></div>
<br>
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