yahoo-eng-team team mailing list archive

[Gorka Eguileor <geguileo@xxxxxxxxxx>]

Public bug reported:

Cinder introduced "shared_targets" and "service_uuid" fields in volumes
to allow volume consumers to protect themselves from unintended leftover
devices when handling iSCSI connections with shared targets.

The way to protect from the automatic scans that happen on detach/map
race conditions is by locking and only allowing one attach or one detach
operation for each server to happen at a given time.

When using an up to date Open iSCSI initiator we don't need to use
locks, as it has the possibility to disable automatic LUN scans (which
are the real cause of the leftover devices), and OS-Brick already
supports this feature.

Currently Nova is blindly locking whenever "shared_targets" is set to
True, even when the iSCSI initiator and OS-Brick are already presenting
such races, which introduces unnecessary serialization on the connection
of volumes.

** Affects: nova
     Importance: Undecided
     Assignee: Gorka Eguileor (gorka)
         Status: New

** Changed in: nova
     Assignee: (unassigned) => Gorka Eguileor (gorka)

-- 
You received this bug notification because you are a member of Yahoo!
Engineering Team, which is subscribed to OpenStack Compute (nova).
https://bugs.launchpad.net/bugs/1800515

Title:
  Unnecessary locking when connecting volumes

Status in OpenStack Compute (nova):
  New

Bug description:
  Cinder introduced "shared_targets" and "service_uuid" fields in
  volumes to allow volume consumers to protect themselves from
  unintended leftover devices when handling iSCSI connections with
  shared targets.

  The way to protect from the automatic scans that happen on detach/map
  race conditions is by locking and only allowing one attach or one
  detach operation for each server to happen at a given time.

  When using an up to date Open iSCSI initiator we don't need to use
  locks, as it has the possibility to disable automatic LUN scans (which
  are the real cause of the leftover devices), and OS-Brick already
  supports this feature.

  Currently Nova is blindly locking whenever "shared_targets" is set to
  True, even when the iSCSI initiator and OS-Brick are already
  presenting such races, which introduces unnecessary serialization on
  the connection of volumes.

To manage notifications about this bug go to:
https://bugs.launchpad.net/nova/+bug/1800515/+subscriptions