@vybava, I just realized the bug description has the exact command sequence you need. But I'm putting again in this comment to make things easier. Please follow the order that was written bellow: ## ## NODE #1 ## # tell "fence_scsi" agent that node 1 is "on" $ sudo fence_scsi --verbose -n 10.250.3.10 -d /dev/sda -k 123abc -o on 2020-02-24 18:37:01,701 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:01,705 DEBUG: 0 2020-02-24 18:37:01,706 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:01,709 DEBUG: 0 2020-02-24 18:37:01,709 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:37:01,712 DEBUG: 0 PR generation=0x2, there are NO registered reservation keys 2020-02-24 18:37:01,714 DEBUG: No registration for key 123abc on device /dev/sda 2020-02-24 18:37:01,714 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:01,718 DEBUG: 0 2020-02-24 18:37:01,718 INFO: Executing: /usr/bin/sg_persist -n -o -I -S 123abc -d /dev/sda 2020-02-24 18:37:01,723 DEBUG: 2 PR out (Register and ignore existing key): Device not ready sg_persist failed: Device not ready 2020-02-24 18:37:01,724 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:01,727 DEBUG: 0 2020-02-24 18:37:01,727 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:37:01,731 DEBUG: 0 PR generation=0x3, 1 registered reservation key follows: 0x123abc 2020-02-24 18:37:01,732 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:01,735 DEBUG: 0 2020-02-24 18:37:01,735 INFO: Executing: /usr/bin/sg_persist -n -i -r -d /dev/sda 2020-02-24 18:37:01,739 DEBUG: 0 PR generation=0x3, there is NO reservation held 2020-02-24 18:37:01,740 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:01,744 DEBUG: 0 2020-02-24 18:37:01,745 INFO: Executing: /usr/bin/sg_persist -n -o -R -T 5 -K 123abc -d /dev/sda 2020-02-24 18:37:01,749 DEBUG: 0 2020-02-24 18:37:01,750 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:01,753 DEBUG: 0 2020-02-24 18:37:01,754 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:01,757 DEBUG: 0 2020-02-24 18:37:01,757 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:37:01,761 DEBUG: 0 PR generation=0x3, 1 registered reservation key follows: 0x123abc Success: Powered ON # key 0x123abc is registered: (k)rafaeldtinoco@clufocal01:~$ sudo sg_persist --in --read-keys --device=/dev/sda LIO-ORG cluster.focal.t 4.0 Peripheral device type: disk PR generation=0x3, 1 registered reservation key follows: 0x123abc # key 0x123abc holds the reservation: (k)rafaeldtinoco@clufocal01:~$ sudo sg_persist -r /dev/sda LIO-ORG cluster.focal.t 4.0 Peripheral device type: disk PR generation=0x3, Reservation follows: Key=0x123abc scope: LU_SCOPE, type: Write Exclusive, registrants only ## ## NODE 02 ## # tell "fence_scsi" agent that node 2 is "on" (k)rafaeldtinoco@clufocal02:~$ sudo fence_scsi --verbose -n 10.250.3.11 -d /dev/sda -k 321abc -o on 2020-02-24 18:37:37,888 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:37,892 DEBUG: 0 2020-02-24 18:37:37,892 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:37,895 DEBUG: 0 2020-02-24 18:37:37,895 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:37:37,901 DEBUG: 0 PR generation=0x3, 1 registered reservation key follows: 0x123abc 2020-02-24 18:37:37,902 DEBUG: No registration for key 321abc on device /dev/sda 2020-02-24 18:37:37,902 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:37,905 DEBUG: 0 2020-02-24 18:37:37,905 INFO: Executing: /usr/bin/sg_persist -n -o -I -S 321abc -d /dev/sda 2020-02-24 18:37:37,910 DEBUG: 2 PR out (Register and ignore existing key): Device not ready sg_persist failed: Device not ready 2020-02-24 18:37:37,910 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:37,913 DEBUG: 0 2020-02-24 18:37:37,913 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:37:37,916 DEBUG: 0 PR generation=0x4, 2 registered reservation keys follow: 0x123abc 0x321abc 2020-02-24 18:37:37,917 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:37,920 DEBUG: 0 2020-02-24 18:37:37,920 INFO: Executing: /usr/bin/sg_persist -n -i -r -d /dev/sda 2020-02-24 18:37:37,923 DEBUG: 0 PR generation=0x4, Reservation follows: Key=0x123abc scope: LU_SCOPE, type: Write Exclusive, registrants only 2020-02-24 18:37:37,924 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:37,927 DEBUG: 0 2020-02-24 18:37:37,928 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:37:37,931 DEBUG: 0 2020-02-24 18:37:37,931 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:37:37,935 DEBUG: 0 PR generation=0x4, 2 registered reservation keys follow: 0x123abc 0x321abc Success: Powered ON # both keys: 0x123abc and 0x321abc are registered to the shared disk (k)rafaeldtinoco@clufocal02:~$ sudo sg_persist --in --read-keys --device=/dev/sda LIO-ORG cluster.focal.t 4.0 Peripheral device type: disk PR generation=0x4, 2 registered reservation keys follow: 0x123abc 0x321abc # key 0x123abc holds the reservation (k)rafaeldtinoco@clufocal02:~$ sudo sg_persist -r /dev/sda LIO-ORG cluster.focal.t 4.0 Peripheral device type: disk PR generation=0x4, Reservation follows: Key=0x123abc scope: LU_SCOPE, type: Write Exclusive, registrants only # from node 2, tell "fence_scsi" agent that node 1 is "off" (k)rafaeldtinoco@clufocal02:~$ sudo fence_scsi --verbose -n 10.250.3.10 -d /dev/sda -k 123abc -o off 2020-02-24 18:38:45,700 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:38:45,704 DEBUG: 0 2020-02-24 18:38:45,705 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:38:45,708 DEBUG: 0 2020-02-24 18:38:45,708 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:38:45,715 DEBUG: 0 PR generation=0x4, 2 registered reservation keys follow: 0x123abc 0x321abc 2020-02-24 18:38:45,716 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:38:45,720 DEBUG: 0 2020-02-24 18:38:45,721 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:38:45,724 DEBUG: 0 PR generation=0x4, 2 registered reservation keys follow: 0x123abc 0x321abc 2020-02-24 18:38:45,725 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:38:45,728 DEBUG: 0 2020-02-24 18:38:45,728 INFO: Executing: /usr/bin/sg_persist -n -o -A -T 5 -K 321abc -S 123abc -d /dev/sda 2020-02-24 18:38:45,732 DEBUG: 0 2020-02-24 18:38:45,732 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:38:45,736 DEBUG: 0 2020-02-24 18:38:45,736 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:38:45,740 DEBUG: 0 PR generation=0x5, 1 registered reservation key follows: 0x321abc 2020-02-24 18:38:45,740 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:38:45,745 DEBUG: 0 2020-02-24 18:38:45,746 INFO: Executing: /usr/bin/sg_persist -n -i -r -d /dev/sda 2020-02-24 18:38:45,751 DEBUG: 0 PR generation=0x5, Reservation follows: Key=0x321abc scope: LU_SCOPE, type: Write Exclusive, registrants only 2020-02-24 18:38:45,754 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:38:45,758 DEBUG: 0 2020-02-24 18:38:45,758 INFO: Executing: /usr/bin/sg_turs /dev/sda 2020-02-24 18:38:45,762 DEBUG: 0 2020-02-24 18:38:45,763 INFO: Executing: /usr/bin/sg_persist -n -i -k -d /dev/sda 2020-02-24 18:38:45,768 DEBUG: 0 PR generation=0x5, 1 registered reservation key follows: 0x321abc 2020-02-24 18:38:45,770 DEBUG: No registration for key 123abc on device /dev/sda Success: Powered OFF # only key 0x321abc (node 2) is registered in the shared disk (k)rafaeldtinoco@clufocal02:~$ sudo sg_persist --in --read-keys --device=/dev/sda LIO-ORG cluster.focal.t 4.0 Peripheral device type: disk PR generation=0x5, 1 registered reservation key follows: 0x321abc # and the key holding the reservation now is 0x321abc (node 2) (k)rafaeldtinoco@clufocal02:~$ sudo sg_persist -r /dev/sda LIO-ORG cluster.focal.t 4.0 Peripheral device type: disk PR generation=0x5, Reservation follows: Key=0x321abc scope: LU_SCOPE, type: Write Exclusive, registrants only