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Diffstat (limited to 'doc')
| -rw-r--r-- | doc/source/reference/compute/libvirt-guide.rst | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/doc/source/reference/compute/libvirt-guide.rst b/doc/source/reference/compute/libvirt-guide.rst index 24a55e1fb..d6212b908 100644 --- a/doc/source/reference/compute/libvirt-guide.rst +++ b/doc/source/reference/compute/libvirt-guide.rst @@ -198,3 +198,26 @@ Since the Yoga release, the ``kolla-ansible certificates`` command generates certificates for libvirt TLS. A single key and certificate is used for all hosts, with a Subject Alternative Name (SAN) entry for each compute host hostname. + +Libvirt Connection Limits +========================= + +By default ``libvirt`` is configured by upstream packages with reasonable +defaults for an environment where many users are starting and stopping virtual +machines. This isn't true for Kolla Hypervisor nodes, where a single +``nova-compute`` container manages all of the virtual machine instances on the +machine. + +Kolla-Ansible therefore tunes the following values in ``libvirtd.conf``: + +* libvirt_max_client_requests: raised to 20 compared to the usual default of + 5. +* libvirt_max_workers: raised to 50 compared to the usual default of 20. + +Both of these values may be overridden in ``globals.yml``. + +This means that ``nova-compute`` can therefore perform 20 operations via +libvirt simultaneously instead of the usual default of 5. These values should +be safe, but if you see libvirt error messages saying ``Client hit max requests +limit``, you may want to consider an additional increase -- especially if you +have particularly large hypervisors. |