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This post demonstrates how to enable Bidirectional or Mutual CHAP on iSCSI luns between Red Hat Enterprise Linux 7 (Beta) and NetApp storage. The aggregate, lun and disk sizes are small in this HOWTO to keep it simple.

1) If not already installed, install the iSCSI initiator on your system.
> yum install iscsi-initiator*

2) Display your server’s new iscsi initiator or iqn nodename.
> cat /etc/iscsi/initiatorname.iscsi

3) On the NetApp filer, create the volume that will hold the iscsi luns. This command assumes you have aggregate aggr1 already created.  If not use an aggregate that has enough room for your volume.
netapp> vol create MCHAPVOL aggr1 10g

4) Create the lun in the volume.
netapp> lun create -s 5g -t linux /vol/MCHAPVOL/RHEL7_iSCSI_MCHAP_01

5) Create an igroup and add the Linux iscsi nodename or iqn from step 2 above to the new igroup.
netapp> igroup create -i -t linux ISCSI_MCHAP_RHEL7
netapp> igroup add ISCSI_MCHAP_RHEL7 iqn.1994-05.com.redhat:ece5618996a9
netapp> igroup show ISCSI_MCHAP_RHEL7

ISCSI_MCHAP_RHEL7 (iSCSI) (ostype: linux):
iqn.1994-05.com.redhat:ece5618996a9 (not logged in)

6) Map the lun to the igroup and give it lun ID 01.
netapp> lun map /vol/MCHAPVOL/RHEL7_iSCSI_MCHAP_01 ISCSI_MCHAP_RHEL7 01

7) Obtain the NetApp target nodename.
netapp> iscsi nodename

8) Set the CHAP secret on the NetApp controller.
netapp> iscsi security add -i iqn.1994-05.com.redhat:ece5618996a9 -s chap -p RHEL7 -n iqn.1994-05.com.redhat:ece5618996a9 -o NETAPPMCHAP -m iqn.1992-08.com.netapp:sn.84167939

netapp> iscsi security show
init: iqn.1994-05.com.redhat:ece5618996a9 auth: CHAP Inbound password: **** Inbound username: iqn.1994-05.com.redhat:ece5618996a9 Outbound password: **** Outbound username: iqn.1992-08.com.netapp:sn.84167939

9) On the server, edit your /etc/iscsi/iscsi.conf file and set the parameters below.
> vi /etc/iscsi/iscsid.conf
node.startup = automatic
node.session.auth.authmethod = CHAP
node.session.auth.username = iqn.1994-05.com.redhat:ece5618996a9
node.session.auth.password = RHEL7
node.session.auth.username_in = iqn.1992-08.com.netapp:sn.84167939
node.session.auth.password_in = NETAPPMCHAP
discovery.sendtargets.auth.authmethod = CHAP
discovery.sendtargets.auth.username = iqn.1994-05.com.redhat:ece5618996a9
discovery.sendtargets.auth.password = RHEL7
discovery.sendtargets.auth.username_in = iqn.1992-08.com.netapp:sn.84167939
discovery.sendtargets.auth.password_in = NETAPPMCHAP
> wq!

10) On the server, restart the service and discover your iSCSI target (your storage system).
> service iscsi restart
Redirecting to /bin/systemctl restart  iscsi.service

a) Verify the target.
> iscsiadm -m discovery -t st -p,1000 iqn.1992-08.com.netapp:sn.84167939

> iscsiadm -m node  (this should display the same as above),1000 iqn.1992-08.com.netapp:sn.84167939

11) On the server, manually login to the iSCSI target (your storage array). Note there are two dashes “- -” in front of targetname and login.
> iscsiadm -m node –targetname “iqn.1992-08.com.netapp:sn.84167939” –login
Logging in to [iface: default, target: iqn.1992-08.com.netapp:sn.84167939, portal:,3260] (multiple)
Login to [iface: default, target: iqn.1992-08.com.netapp:sn.84167939, portal:,3260] successful.

a) On the NetApp storage console you should see the iSCSI session:
[iscsi.notice:notice]: ISCSI: New session from initiator iqn.1994-05.com.redhat:ece5618996a9 at IP addr

b) Verify the iSCSI session on the filer:
netapp> iscsi session show
Session 88
Initiator Information
Initiator Name: iqn.1994-05.com.redhat:ece5618996a9
ISID: 00:02:3d:01:00:00
Initiator Alias: rhel7

12) From the server , check your session.
> iscsiadm -m session -P 1
Target: iqn.1992-08.com.netapp:sn.84167939
Current Portal:,1000
Persistent Portal:,1000
Iface Name: default
Iface Transport: tcp
Iface Initiatorname: iqn.1994-05.com.redhat:ece5618996a9
Iface IPaddress:
Iface HWaddress: <empty>
Iface Netdev: <empty>
SID: 1
iSCSI Connection State: LOGGED IN
iSCSI Session State: LOGGED_IN
Internal iscsid Session State: NO CHANGE

13) From the server, check the NetApp iSCSI details. Note there are two dashes “- -” in front of mode, targetname and portal.
> iscsiadm –mode node –targetname “iqn.1992-08.com.netapp:sn.84167939” –portal

14) From the server, find and format the new lun (new disk). Your fdisk commands are in bold red below.
> cat /var/log/messages | grep “unknown partition table”
rhel7 kernel: [   24.102281]  sdb: unknown partition table

> fdisk /dev/sdb

Welcome to fdisk (util-linux 2.23.2).

Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.

Device does not contain a recognized partition table
Building a new DOS disklabel with disk identifier 0x2c025f67.

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.
Syncing disks.

> fdisk /dev/sdb
Command (m for help): n
Partition type:
p   primary (0 primary, 0 extended, 4 free)
e   extended
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-10485759, default 2048): <press enter>
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-10485759, default 10485759): <press enter>
Using default value 10485759
Partition 1 of type Linux and of size 5 GiB is set

Command (m for help): p
Disk /dev/sdb: 5368 MB, 5368709120 bytes, 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xeb560917

Device Boot  Start  End       Blocks   Id  System
/dev/sdb1    2048   10485759  5241856  83  Linux

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.

15) On the server, create the Linux file system on the new partition.
> mkfs -t ext4 /dev/sdb1
mke2fs 1.42.8 (20-Jun-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=0 blocks
327680 inodes, 1310464 blocks
65523 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1342177280
40 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736

Allocating group tables: done
Writing inode tables: done
Creating journal (32768 blocks): done
Writing superblocks and filesystem accounting information: done

16) Verify the partition.
> blkid /dev/sdb1
/dev/sdb1: UUID=”540997d7-ee07-42b3-a4af-612af6812d18″ TYPE=”ext4″

17) Create the mount point and manually mount the directory.
> mkdir /newiscsilun
> mount /dev/sdb1 /newiscsilun
> df -h | grep newiscsilun
Filesystem Size  Used Avail Use% Mounted on
/dev/sdb1  4.8G  10M  4.6G   1% /newiscsilun

18) Add the new mount point to /etc/fstab.
> vi /etc/fstab
/dev/sdb1 /newiscsilun ext4 _netdev 0 0
> wq!

Note: the _netdev option is important so that it doesn’t try mounting the target before the network is available.

19) Test that it survives a reboot by rebooting the server. With the _netdev set, iscsi starts and your CHAP logins should take place before it attempts to mount. After the reboot, login and verify its mounted.

> df -h | grep newiscsilun
Filesystem Size  Used Avail Use% Mounted on
/dev/sdb1  5.0G  139M  4.6G   3% /newiscsilun

20) On the server you can check session stats.
> iscsiadm -m session -s
Stats for session [sid: 1, target: iqn.1992-08.com.netapp:sn.84167939, portal:,3260]
txdata_octets: 17096
rxdata_octets: 748232
noptx_pdus: 0
scsicmd_pdus: 213
tmfcmd_pdus: 0
login_pdus: 0
text_pdus: 0
dataout_pdus: 0
logout_pdus: 0
snack_pdus: 0
noprx_pdus: 0
scsirsp_pdus: 213
tmfrsp_pdus: 0
textrsp_pdus: 0
datain_pdus: 204
logoutrsp_pdus: 0
r2t_pdus: 0
async_pdus: 0
rjt_pdus: 0
digest_err: 0
timeout_err: 0
iSCSI Extended:
tx_sendpage_failures: 0
rx_discontiguous_hdr: 0
eh_abort_cnt: 0

21) As root, change permissions on /etc/iscsi/iscsid.conf. I’m not sure why they haven’t fixed this clear text CHAP password in a file issue so just make sure only root can read/write the file.
> chmod 600 /etc/iscsi/iscsid.conf

22) On the NetApp storage you can verify the Lun and the server’s session.
> lun show -v /vol/MCHAPVOL/RHEL7_iSCSI_MCHAP_01
/vol/MCHAPVOL/RHEL7_iSCSI_MCHAP_01      5g (5368709120)    (r/w, online, mapped)
Serial#: hoagPJvrDTup
Share: none
Space Reservation: enabled (not honored by containing Aggregate)
Multiprotocol Type: linux

> iscsi session show -v
Session 90
Initiator Information
Initiator Name: iqn.1994-05.com.redhat:ece5618996a9
ISID: 00:02:3d:01:00:00
Initiator Alias: rhel7

Session Parameters
Initiator MaxRecvDataSegmentLength=65536
Target MaxRecvDataSegmentLength=65536
Command Window Size: 32

Connection Information
Connection 0
Remote Endpoint:
Local Endpoint:
Local Interface: e0a
TCP recv window size: 131400

Command Information
No commands active