iSCSI tgtd does not start properly on boot (works after service restart)

Hi,

I'm using  Armbian 21.08.6 Bullseye on an Odroid HC2 (http://ix.io/3JUu). I set up tgt (Linux iSCSI) and everything works fine (clients can access the targets). The targets are stored on a btrfs volume.

fstab content:

UUID=4d27c22c-348e-4d96-8d6d-0bed3cc7f965		/	ext4	noatime,nodiratime,defaults,commit=600,errors=remount-ro	0 1
tmpfs /tmp tmpfs defaults,nosuid 0 0
/dev/disk/by-uuid/23e54a5b-e08b-49a9-af88-cffc88d9e84e		/srv/dev-disk-by-uuid-23e54a5b-e08b-49a9-af88-cffc88d9e84e	btrfs	defaults,nofail	0 2

However, when a reboot occurs, tgtd seems to not start properly:

• Clients cannot access the targets.
• tgtadm shows `backing store path: None`

Full output:

nas:~:# tgtadm --lld iscsi --mode target --op show
Target 1: iqn.2021-12.odroidxu4:test
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00010000
            SCSI SN: beaf10
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: No
            Backing store type: null
            Backing store path: None
            Backing store flags: 
    Account information:
    ACL information:
        ALL
Target 2: iqn.2021-12.odroidxu4:testf
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
        I_T nexus: 1
            Initiator: iqn.1991-05.com.microsoft:sirius alias: none
            Connection: 1
                IP Address: 192.168.50.26
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00020000
            SCSI SN: beaf20
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: No
            Backing store type: null
            Backing store path: None
            Backing store flags: 
    Account information:
    ACL information:
        ALL

However after restarting the tgtd with `systemctl restart tgt.service`, everything works fine again. tgtadm output: (Note that `Backing store path`is set).

nas:~:# tgtadm --lld iscsi --mode target --op show
Target 1: iqn.2021-12.odroidxu4:test
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00010000
            SCSI SN: beaf10
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: No
            Backing store type: null
            Backing store path: None
            Backing store flags: 
        LUN: 1
            Type: disk
            SCSI ID: IET     00010001
            SCSI SN: beaf11
            Size: 536871 MB, Block size: 512
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: No
            Backing store type: rdwr
            Backing store path: /srv/dev-disk-by-uuid-23e54a5b-e08b-49a9-af88-cffc88d9e84e/backup-nb-regina/test
            Backing store flags: 
    Account information:
    ACL information:
        ALL
Target 2: iqn.2021-12.odroidxu4:testf
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
        I_T nexus: 1
            Initiator: iqn.1991-05.com.microsoft:sirius alias: none
            Connection: 1
                IP Address: 192.168.50.26
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00020000
            SCSI SN: beaf20
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: No
            Backing store type: null
            Backing store path: None
            Backing store flags: 
        LUN: 1
            Type: disk
            SCSI ID: IET     00020001
            SCSI SN: beaf21
            Size: 1073742 MB, Block size: 512
            Online: Yes
            Removable media: No
            Prevent removal: No
            Readonly: No
            SWP: No
            Thin-provisioning: No
            Backing store type: rdwr
            Backing store path: /srv/dev-disk-by-uuid-23e54a5b-e08b-49a9-af88-cffc88d9e84e/backup-nb-regina/testf
            Backing store flags: 
    Account information:
    ACL information:
        ALL

I worked around this issue by adding a `ExecStartPre=/bin/sleep 60` to the `tgt.service` unit.

However, I would like to solve the issue substantially. Does anybody have an idea how to debug/solve this?

Best,

exponentialverteilt