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.
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
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.
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.
I will update the issue on github with the list of expected storage providers
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
[email protected]<mailto:[email protected]>
@cantbewong
From: Marica Antonacci [mailto:[email protected]]
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
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?
...
