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https://bugzilla.redhat.com/show_bug.cgi?id=1152382 When libvirt create's the vport (VPORT_CREATE) for the vHBA, there isn't enough "time" between the creation and the running of the following backend->refreshPool after a backend->startPool in order to find the LU's. Population of LU's happens asynchronously when udevEventHandleCallback discovers the "new" vHBA port. Creation of the infrastructure by udev is an iterative process creating and discovering actual storage devices and adjusting the environment. Because of the time it takes to discover and set things up, the backend refreshPool call done after the startPool call will generally fail to find any devices. This leaves the newly started pool appear empty when querying via 'vol-list' after startup. The "workaround" has always been to run pool-refresh after startup (or any time thereafter) in order to find the LU's. Depending on how quickly run after startup, this too may not find any LUs in the pool. Eventually though given enough time and retries it will find something if LU's exist for the vHBA. This patch adds a thread to be executed after the VPORT_CREATE which will attempt to find the LU's without requiring the external run of refresh-pool. It does this by waiting for 5 seconds and searching for the LU's. If any are found, then the thread completes; otherwise, it will retry once more in another 5 seconds. If none are found in that second pass, the thread gives up. Things learned while investigating this... No need to try and fill the pool too quickly or too many times. Over the course of creation, the udev code may 'add', 'change', and 'delete' the same device. So if the refresh code runs and finds something, it may display it only to have a subsequent refresh appear to "lose" the device. The udev processing doesn't seem to have a way to indicate that it's all done with the creation processing of a newly found vHBA. Only the Lone Ranger has silver bullets to fix everything.
LibVirt : simple API for virtualization
Libvirt is a C toolkit to interact with the virtualization capabilities
of recent versions of Linux (and other OSes). It is free software
available under the GNU Lesser General Public License. Virtualization of
the Linux Operating System means the ability to run multiple instances of
Operating Systems concurrently on a single hardware system where the basic
resources are driven by a Linux instance. The library aim at providing
long term stable C API initially for the Xen paravirtualization but
should be able to integrate other virtualization mechanisms if needed.
Daniel Veillard <veillard@redhat.com>