We have a situation where tenant A is trying to launch large numbers of
instances from a single RBD volume snapshot in Cinder (e.g., 40 instances at
once). We made an unrelated change recently to enable
rbd_flatten_volume_from_snapshot by default in order to save tenants who create
large chains of volumes and snapshots until they run out of quota and then
can't figure out how to unwind the chain, because the relationships are not
trivially traceable. This change appears to be causing tenant A significant
heartache now, because when he launches some large number of instances at once,
most of his instance launches time out, presumably because Cinder is stampeding
onto Ceph and trying to create flattened RBD images for every single instance
simultaneously.
My question is, is there anything I can do to stop this stampeding? A review of
cinder.conf options for Kilo didn't point out any obvious setting that could be
adjusted to force Cinder to serialize its operations here, but maybe I missed
something.
_______________________________________________
OpenStack-operators mailing list
OpenStack-operators@lists.openstack.org
http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
