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 -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : yahoo-eng-team@lists.launchpad.net Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp