[openstack-dev] [nova] Request Spec Freeze Exception (DRBD for Nova)

Philipp Marek philipp.marek at linbit.com
Fri Jan 30 08:55:45 UTC 2015

Hi all,

> in Paris (and later on, on IRC and the mailing list) I began to ask around 
> about providing a DRBD storage driver for Nova.
> This is an alternative to using iSCSI for block storage access, and would 
> be especially helpful for backends already using DRBD for replicated 
> storage.
any news about this?

To reiterate:
  * Spec was submitted in time (Nov 13)
  * Spec wasn't approved, because the Cinder implementation
    (https://review.openstack.org/#/c/140451/) merge got delayed,
    because its prerequisite (https://review.openstack.org/#/c/135139/,
    Transition LVM Driver to use Target Objects) wasn't merged in time,
    because on "deadline day" (Dec. 17) Gerrit was so much used that
    this devstack run got timeouts against some python site during
  * "Spec Freeze Exception" was submitted in time
  * Having DRBD for Cinder is good, but using the *same* protocol
    to the Nova nodes should really help performance (and reliability);
    for example, the transitions
      Network -> Kernel -> iSCSI daemon -> Kernel -> Block Device
    wouldn't be needed anymore; the Kernel could directly respond to the
    queries, and in the near future even using RDMA (where available).
    Reliability should be improved as the Nova node can access multiple
    storage nodes _at the same time_, so it wouldn't matter if one of them
    crashes for whatever reason.

Please help us *now* to get the change in. It's only a few lines in
a separate driver, so until it gets configured it won't even be

And yes, of course we're planning to do CI for that Nova driver, too.


: Ing. Philipp Marek
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting                 http://www.linbit.com :

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