Configure Storage Server with iSCSI.
This is the example of configuring iSCSI Target with scsi-target-utils. (tgt)
Storage server with iSCSI on network is called iSCSI Target, Client Host that connects to iSCSI Target is called iSCSI Initiator.
This example is based on the environment like follows

+----------------------+          |          +----------------------+
| [   iSCSI Target   ] |10.0.0.30 | 10.0.0.51| [ iSCSI Initiator  ] |
|     iscsi.srv.local  +----------+----------+   client.srv.local   |
|                      |                     |                      |
+----------------------+                     +----------------------+

[1] Install administration tools.

root@iscsi:~# apt -y install tgt

[2] Configure iSCSI Target.

For example, create an disk-image under the [/var/lib/iscsi_disks] directory and set it as a SCSI device.

# create a disk image
root@iscsi:~# mkdir /var/lib/iscsi_disks
root@iscsi:~# dd if=/dev/zero of=/var/lib/iscsi_disks/disk01.img count=0 bs=1 seek=10G
root@iscsi ~# vi /etc/tgt/conf.d/target01.conf
# create new
# if you set some devices, add <target>-</target> and set the same way with follows
# naming rule : [ iqn.(year)-(month).(reverse of domain name):(any name you like) ]
<target iqn.2022-10.local.srv:iscsi.target01>
    # provided devicce as a iSCSI target
    backing-store /var/lib/iscsi_disks/disk01.img
    # iSCSI Initiator's IQN you allow to connect
    initiator-name iqn.2022-10.local.srv:client.initiator01
    # authentication info ( set anyone you like for "username", "password" )
    incominguser username password
</target> 

root@iscsi:~# systemctl restart tgt
# show status
root@iscsi:~# tgtadm --mode target --op show
Target 1: iqn.2022-10.local.srv:iscsi.target01
    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: 10737 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: /var/lib/iscsi_disks/disk01.img
            Backing store flags:
    Account information:
        username
    ACL information:
        ALL
        iqn.2022-10.local.srv:client.initiator01