Mounting iSCSI in CentOS 7

Tested on CentOS 7 and Fedora 25/26.

Install package ''iscsi-initiator-utils''.

iSCSI server is 192.168.22.22

Discovery

Find out the target names. I'll assume there is only one target.

$ sudo iscsiadm -m discovery -t sendtargets -p nas02.swehack.local
192.168.22.22:3260,1 iqn.2017-18.local.swehack:nas02.target1

Basic login without CHAP. Just copy most of the values from the discovery step.

$ sudo iscsiadm --mode node --targetname iqn.2017-18.local.swehack:nas02.target1 --portal 192.168.22.22:3260,1 --login

Basic initiator authentication

This requires no login info and is usually restricted by client IP. Just edit ''/etc/iscsid/initiatorname.iscsi'' and add the InitiatorName.

InitiatorName=iqn.2017-18.local.swehack:nas02.target1

CHAP Authentication

In ''/etc/iscsi/iscsid.conf'' you can see the following options for CHAP authentication.

node.session.auth.username
node.session.auth.password
discovery.sendtargets.auth.username
discovery.sendtargets.auth.password

Using devices

To find out which devices are being exposed to your client. This will list all your targets so you'll have to scroll to the one you want.

$ sudo iscsiadm -m session -P 3
...
            Attached SCSI devices:

            ************************                                                                                                                                                                           
            Host Number: 11 State: running                                                                                                                                                                     
            scsi11 Channel 00 Id 0 Lun: 0                                                                                                                                                                      
            scsi11 Channel 00 Id 0 Lun: 1                                                                                                                                                                      
                    Attached scsi disk sdf          State: running                                                                                                                                             
            scsi11 Channel 00 Id 0 Lun: 2                                                                                                                                                                      
                    Attached scsi disk sdh          State: running

WWN for devices

In my experience those names aren't reliable (/dev/sdg) so to find out the WWN that will not change across reboots/session changes you can do this.

$ ls -l /dev/disk/by-id/wwn-*
...
/dev/disk/by-id/wwn-0x60000000000000000e00000000010001 -> ../../sdg
/dev/disk/by-id/wwn-0x60000000000000000e00000000010002 -> ../../sdh

These won't change and can be used in virtual machines as storage for example.

You can also use by-path which should also remain unchanged as long as you don't change your NAS or target.

/dev/disk/by-path/ip-192.168.22.22:3260-iscsi-iqn.2017-18.local.swehack:nas02.target1-lun-1

Rescan for new LUNs

Find out your session ID.

$ sudo iscsiadm -m session
tcp: [6] ...

Rescan that session ID.

$ sudo iscsiadm -m session --sid=6 --rescan