Hi Bernd,

Thank you for help.

When I checked about volume 5d66b469-... in the cinder volume logs. I found something like that:

2020-02-11 16:19:51.363 4392 ERROR cinder.volume.flows.manager.create_volume [req-8679a108-63d5-4b62-b22c-9368c00cb0ee fe13f558610b4c23a3b54603090f3f26 4cf7db9bef75434892051eb77a2c0ba9 - default default] Volume 5d66b469-95d0-4c95-849f-9cf61f0e6740: create failed
2020-02-11 16:39:08.677 4392 ERROR cinder.volume.volume_utils [req-df863b56-02af-4ed7-9e8c-cb21642b1dd7 fe13f558610b4c23a3b54603090f3f26 4cf7db9bef75434892051eb77a2c0ba9 - default default] Failed to copy image 88547948-e2a1-4798-be08-d610c72d5dcf to volume: 9aba7d18-2c06-4f62-9327-a989ca58c530: ProcessExecutionError: Unexpected error while running command.

I checked that Cinder service is running well as followings:

[root@localhost ~(keystone_admin)]# openstack volume service list
+------------------+---------------------------+------+---------+-------+----------------------------+
| Binary           | Host                      | Zone | Status  | State | Updated At                 |
+------------------+---------------------------+------+---------+-------+----------------------------+
| cinder-scheduler | localhost.localdomain     | nova | enabled | up    | 2020-02-11T22:32:04.000000 |
| cinder-backup    | localhost.localdomain     | nova | enabled | up    | 2020-02-11T22:32:05.000000 |
| cinder-volume    | localhost.localdomain@lvm | nova | enabled | up    | 2020-02-11T22:32:10.000000 |
+------------------+---------------------------+------+---------+-------+----------------------------+

When I launced an instance without volume. This time I got an error as follows:

Error: Failed to perform requested operation on instance "web", the instance has an error status: Please try again later [Error: Exceeded maximum number of retries. Exhausted all hosts available for retrying build failures for instance 2191a1bb-50c5-46fb-b0cd-64f1716ac2ba.].

I also checked volume groups and logical volumes as can be seen below:

[root@localhost ~(keystone_admin)]# pvs
  PV         VG             Fmt  Attr PSize   PFree  
  /dev/loop1 cinder-volumes lvm2 a--  <20.60g      0 
  /dev/sda2  centos         lvm2 a--  <19.00g      0 
  /dev/sdb1  cinder-volumes lvm2 a--  <30.00g <14.65g
  /dev/sdc1                 lvm2 ---  <10.00g <10.00g

[root@localhost ~(keystone_admin)]# vgs
  VG             #PV #LV #SN Attr   VSize   VFree  
  centos           1   2   0 wz--n- <19.00g      0 
  cinder-volumes   2   1   0 wz--n-  50.59g <14.65g

[root@localhost ~(keystone_admin)]# lvs
  LV                  VG             Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root                centos         -wi-ao---- <17.00g                                                    
  swap                centos         -wi-ao----   2.00g                                                    
  cinder-volumes-pool cinder-volumes twi-aotz--  30.98g             0.00   0.64

Unfortunately, I didn't find any solution. I keep looking for it on the internet and other platforms.