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List: mesos-user
Subject: RE: external storage with dvdi module
From: "Wong, Steven" <steven.wong () emc ! com>
Date: 2015-11-20 20:02:27
Message-ID: 70E51508176DB54CADCB126E070747B52E982FEB () MX107CL02 ! corp ! emc ! com
[Download RAW message or body]
Storage providers fall into two categories, those that explicitly have arch=
itected API support for pre-emptive mount and those that require custom cod=
ing and orchestration.
I anticipate that OpenStack cinder will be supported for pre-emptive mount.
Another consideration: if the scenario is not Mesos agent shutdown or crash=
, but instead a network partitioning event. Wihere the agent cluster node c=
ontinues t run, but is seen as equivalent to a crash by the Mesos Master, t=
he OpenStack cinder volume will be abruptly "torn away" from the original m=
ounter. Should this occur midstream during a write, there is the possibilit=
y that it would result in some form of data corruption.
I expect that OpenStack cinder pre-emptive mount will be delivered in the n=
ext major release of the rexray driver along with Amazon EBS pre-emptive mo=
unts and others TBD.
I will update the issue on github with the list of expected storage provide=
rs as I get closer to delivery.
Steve Wong
Contributor to the Mesos dvdi module project
Developer Advocate
EMC{code} - the open source advocacy group within EMC
CODE OPEN, DEPLOY EVERYWHERE
https://github.com/emccode
blog.emccode.com
1.562.417.7048
steven.wong@emc.com<mailto:steven.wong@emc.com>
@cantbewong
From: Marica Antonacci [mailto:marica.antonacci@ba.infn.it]
Sent: Friday, November 20, 2015 12:44 AM
To: Wong, Steven
Subject: Re: external storage with dvdi module
Dear Steven,
thank you very much for your detailed reply; I think that pre-emptive mount=
capability will be certainly a valuable addition.
As far as I understand, this feature will depend mainly on the underlying s=
torage layer and will work only if a related capability is exposed by the s=
torage component itself. For example, concerning Openstack Cinder the pre-e=
mptive mount is not currently supported and there is a blueprint (approved =
but not implemented yet) for enabling the multiple attachments of a single =
volume. The roadmap for such addition in cinder is not clear to me yet...wh=
at will be the behavior of the dvdi module (and the openstack storage drive=
r) in the meanwhile?
...
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<p class="MsoNormal"><span \
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Storage \
providers fall into two categories, those that explicitly have architected API \
support for pre-emptive mount and those that require custom coding and \
orchestration.<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"><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">I \
anticipate that OpenStack cinder will be supported for pre-emptive \
mount.<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">Another \
consideration: if the scenario is not Mesos agent shutdown or crash, but instead a \
network partitioning event. Wihere the agent cluster node continues t run, but is \
seen as equivalent to a crash by the Mesos Master, the OpenStack cinder volume will \
be abruptly “torn away” from the original mounter. Should this occur \
midstream during a write, there is the possibility that it would result in some form \
of data corruption. <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">I \
expect that OpenStack cinder pre-emptive mount will be delivered in the next major \
release of the rexray driver along with Amazon EBS pre-emptive mounts and others \
TBD.<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">I \
will update the issue on github with the list of expected storage providers as I get \
closer to delivery. <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"></span>Steve \
Wong<br> Contributor to the Mesos dvdi module project <br>
Developer Advocate<br>
EMC{code} - the open source advocacy group within EMC<br>
<br>
CODE OPEN, DEPLOY EVERYWHERE<br>
<a href="https://github.com/emccode">https://github.com/emccode</a><br>
blog.emccode.com<br>
<br>
1.562.417.7048<br>
<a href="mailto:steven.wong@emc.com">steven.wong@emc.com</a><br>
@cantbewong<o:p></o:p></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"><o:p> </o:p></span></p>
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<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in">
<p class="MsoNormal"><b><span \
style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span \
style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> \
Marica Antonacci [mailto:marica.antonacci@ba.infn.it] <br>
<b>Sent:</b> Friday, November 20, 2015 12:44 AM<br>
<b>To:</b> Wong, Steven<br>
<b>Subject:</b> Re: external storage with dvdi module<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Dear Steven,<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">thank you very much for your detailed reply; I think that \
pre-emptive mount capability will be certainly a valuable \
addition. <o:p></o:p></p> </div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal">As far as I understand, this feature will depend mainly on the \
underlying storage layer and will work only if a related capability is exposed by the \
storage component itself. For example, concerning Openstack Cinder the pre-emptive \
mount is not currently supported and there is a blueprint (approved but not \
implemented yet) for enabling the multiple attachments of a single volume. The \
roadmap for such addition in cinder is not clear to me yet…what will be the \
behavior of the dvdi module (and the openstack storage driver) in the \
meanwhile?<o:p></o:p></p> </div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><span \
style="color:#1F497D">…</span><br> <br>
<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
</div>
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</body>
</html>
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