Seen here:
http://logs.openstack.org/69/530969/1/check/tempest-full/223c175/controller/logs/screen-c-sch.txt
VolumesBackupsTest-1618334087 None] Checking if host ubuntu-xenial-inap-mtl01-0001669860@lvmdriver-1#lvmdriver-1 can create a 1 GB volume (907e0662-4844-4b30-ae69-07c01482d36a) {{(pid=13148) backend_passes /opt/stack/cinder/cinder/scheduler/filters/capacity_filter.py:62}}
Jan 03 17:51:40.739901 ubuntu-xenial-inap-mtl01-0001669860 cinder-scheduler[13148]: WARNING cinder.scheduler.filters.capacity_filter [None req-b28e1f6d-4c44-40ee-b529-4c05b4f64fb5 tempest-VolumesBackupsTest-1618334087 None] Insufficient free virtual space (-10.6GB) to accommodate thin provisioned 1GB volume on host ubuntu-xenial-inap-mtl01-0001669860@lvmdriver-1#lvmdriver-1.
Jan 03 17:51:40.740001 ubuntu-xenial-inap-mtl01-0001669860 cinder-scheduler[13148]: DEBUG cinder.scheduler.base_filter [None req-b28e1f6d-4c44-40ee-b529-4c05b4f64fb5 tempest-VolumesBackupsTest-1618334087 None] Filter CapacityFilter returned 0 host(s) {{(pid=13148) get_filtered_objects /opt/stack/cinder/cinder/scheduler/base_filter.py:125}}
http://logstash.openstack.org/#dashboard/file/logstash.json?query=message%3A%5C%22Insufficient%20free%20virtual%20space%5C%22%20AND%20message%3A%5C%22to%20accommodate%20thin%20provisioned%201GB%20volume%20on%5C%22%20AND%20tags%3A%5C%22screen-c-sch.txt%5C%22&from=7d
11 hits in 7 days, check and gate, all failures, looks like it maybe started around Jan 1.
More recent occurrence of the issue: http:// logs.openstack. org/64/ 519664/ 3/check/ tempest- full/dbb3f0e/ controller/ logs/screen- c-sch.txt. gz#_Jan_ 23_18_55_ 00_424738
Analysis of the issue (according to logs from Cinder scheduler):
Jan 23 18:54:11.059512 - scheduler receives status update with free_capacity_gb = 9.47
Jan 23 18:54:11.169724 - filter reports that free_capacity_gb: 9.47
Jan 23 18:54:12.503192 - filter reports that free_capacity_gb: 8.47
....
Jan 23 18:54:57.731754 - filter reports that free_capacity_gb: 0.47
Jan 23 18:55:00.424738 - Insufficient free virtual space (-10.6GB)
Value -10.6 is calculated and one of ways to get it is when backend_ state.free_ capacity_ gb = -0.53 (https:/ /github. com/openstack/ cinder/ blob/master/ cinder/ scheduler/ filters/ capacity_ filter. py#L74- L142)
The next status update goes at Jan 23 18:55:05.453072 and it resets the free space value back to 9.47
To sum up: between 2 updates of capacity numbers scheduler allocates a number of volumes; each allocation reduces local value of free disk space, until it gets below 0.