Comment 2 for bug 1546049

size of /dev/sdb4 was 69819M

4:425MiB:70244MiB:69819MiB::primary:;

pv was created with --metadatacopies 2 --metadatasize 28m (so, 28*2 expected to be reserved for lvm service needs)

2016-02-15 10:02:37 INFO fuel_agent.utils.lvm [-] Found physical volumes: [{'uuid': 'D9yvra-Y48g-PZe1-BnFq-ogah-cCeZ-jIAAOO', 'devsize': 69819, 'name': '/dev/sdb4', 'psize': 69819, 'vg': None}]
2016-02-15 10:02:37 INFO fuel_agent.utils.utils [-] Trying to execute command: pvdisplay -C --noheading --units m --options pv_name,vg_name,pv_size,dev_size,pv_uuid --separator ;
2016-02-15 10:02:37 INFO fuel_agent.utils.utils [-] Trying to execute command: pvcreate --metadatacopies 2 --metadatasize 28m /dev/sdb4

but then

2016-02-15 10:02:38 INFO fuel_agent.utils.lvm [-] Found volume groups: [{'size': 69740, 'name': 'os', 'free': 69740, 'uuid': 'HHJqnA-tEDc-ixFO-U7M0-FHYM-ruLS-EtQeyo'}]
2016-02-15 10:02:38 INFO fuel_agent.utils.utils [-] Trying to execute command: vgdisplay -C --noheading --units m --options vg_name,vg_uuid,vg_size,vg_free --separator ;
2016-02-15 10:02:38 INFO fuel_agent.utils.utils [-] Trying to execute command: vgcreate os /dev/sdb4

vg os has got only 69740M (expected value was 69819 - 56 = 69763, that is 23M shorter than expected)

therefore, fuel-agent ended up with
2016-02-15 10:02:38 INFO fuel_agent.cmd.agent NotEnoughSpaceError: Error while creating lv: vg os has only 16368 m of free space, but at least 16384 m is needed

RC: for some reasons, created lvm logical volume occupied more space than expected. Underestimated size is roughly within 12-16M.