[Bug 1028718] Re: nova volumes are inappropriately clingy for ceph and similar drivers

[Sean McGinnis]

I believe this is no longer relevant. Please let me know if that is not
the case.

** Changed in: cinder
       Status: Triaged => Invalid

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https://bugs.launchpad.net/bugs/1028718

Title:
  nova volumes are inappropriately clingy for ceph and similar drivers

Status in Cinder:
  Invalid
Status in nova package in Ubuntu:
  Invalid

Bug description:
  I've been doing a little work with nova-volume and ceph/RBD.  In order
  to gain some fault-tolerance, I plan to run a nova-volume on each
  compute node.  However, a problem arises, because a given nova-volume
  host only wants to deal with requests for volumes that it created.

  This makes perfect sense in a world where nova-volume hosts create
  volumes in LVM and export them over iSCSI.  It makes less sense in a
  Ceph world, since the volumes live in the ceph cluster, and their
  metadata live in the nova database.  But if the wrong nova-volume goes
  away, some of my volumes become arbitrarily unusable.

  I've hit upon a workaround that seems to work so far, although I'm not
  sure if it's supposed to.  I am running each nova-volume on the
  various hosts with an identical --host flag.  When running in this
  setup, rapid volume creation, deletion and attachment requests are
  splayed nicely across the nova-volume instances.

  (A less brutal hack might be to teach nova-volume to call into the
  volume driver to check if it has its own notion of what the host flag
  ought to be -- the RBD driver, for example, could construct a string
  such as "ceph:67670443-07ad-4ce3-bdb8-75e9a14562f9:rbd" by probing the
  Ceph cluster for its fsid, which ought to be unique, and then
  appending the name of the RADOS pool in which it is creating RBDs.)

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