<div dir="ltr"><div>Hi, I'm trying to use lvm thin provisioning with openstack cinder (mitaka) but I have a problem with snapshots. I'm trying to create a snapshot from a volume (detached) and then create a new volume from the snapshot.<br><br></div>1) Snapshot creation works well and I have (with lvs)<br><br>  LV                                             VG              Attr       LSize  Pool                 Origin                                      Data%  Meta%  Move Log Cpy%Sync Convert<br>  <b>_snapshot-f702a3b0-e021-471b-80c3-56cab0c1c1e6 cinder-volumes2 Vwi---tz-k  1.00g cinder-volumes2-pool volume-a60699c5-55c2-4dbc-b74a-64b51f2f4dd2</b>                                        <br>  activationvol                                  cinder-volumes2 -wi-a----- 16.00m                                                                                                         <br>  cinder-volumes2-pool                           cinder-volumes2 twi-aotz-- 18.98g                                                                  0.00   0.59                            <br>  <b>volume-a60699c5-55c2-4dbc-b74a-64b51f2f4dd2    cinder-volumes2 Vwi-a-tz--  1.00g cinder-volumes2-pool                                             0.00</b>                                   <br><br><div>2) When I try to create the new volume from the snapshot I have an error: /bin/dd: failed to open /dev/mapper/cinder--volumes2-_snapshot--f702a3b0--e021--471b--80c3--56cab0c1c1e6\xe2\x80\x99: No such file or directory\n'<br></div><div>But the new logical volume is created in the pool:<br><br>[root@mitaka-cinder-volume1-env3 ~]# lvs<br>  LV                                             VG              Attr       LSize  Pool                 Origin                                      Data%  Meta%  Move Log Cpy%Sync Convert<br>  _snapshot-f702a3b0-e021-471b-80c3-56cab0c1c1e6 cinder-volumes2 Vwi---tz-k  1.00g cinder-volumes2-pool volume-a60699c5-55c2-4dbc-b74a-64b51f2f4dd2                                        <br>  activationvol                                  cinder-volumes2 -wi-a----- 16.00m                                                                                                         <br>  cinder-volumes2-pool                           cinder-volumes2 twi-aotz-- 18.98g                                                                  0.00   0.59                            <br>  volume-86666116-660f-4bfc-a27e-fa5e689578ce    cinder-volumes2 Vwi-a-tz--  1.00g cinder-volumes2-pool                                             0.00                                   <br>  volume-a60699c5-55c2-4dbc-b74a-64b51f2f4dd2    cinder-volumes2 Vwi-a-tz--  1.00g cinder-volumes2-pool                                             0.00                                   <br><br><br></div><div>The problem is that in /dev/mapper I don't have the link associated with the "snapshot" device. Is this a problem related to the operating system configuration? Or I missing something in cinder.conf?? Should I modify some setting in /etc/lvm/lvm.conf?<br><br>More details about my configuration:<br>[root@mitaka-cinder-volume1-env3 ~]# cat /etc/redhat-release <br>CentOS Linux release 7.3.1611 (Core) <br>[root@mitaka-cinder-volume1-env3 ~]# rpm -qa | grep lvm<br>lvm2-libs-2.02.166-1.el7_3.1.x86_64<br>lvm2-2.02.166-1.el7_3.1.x86_64<br><br>My configuration in cinder.conf:<br><br>[lvm2]<br>volume_driver = cinder.volume.drivers.lvm.LVMVolumeDriver<br>volume_group = cinder-volumes2<br>volume_backend_name = LVM_iSCSI2<br>iscsi_protocol = iscsi<br>iscsi_helper = lioadm<br>iscsi_ip_address= 192.168.203.4<br>volume_clear=zero<br>volume_clear_size=30<br>lvm_type = thin<br>lvm_conf_file = /etc/cinder/lvm.conf <-- locking_type = 1, use_lvmetad = 0, volume_list = [ "@pacemaker" ]   (I'm using an active/passive cluster with an LVM resource for cinder-volumes2 VG)<br>max_over_subscription_ratio = 1.0<br><br><br></div><div>It seems that if I use thin provisioning the snapshot device doesn't exists even though I see it with lvm so dd command fails.<br></div><div>I'm a bit confused. Any help will be really appreciated<br><br></div><div>Thank you <br></div></div>