RHEL: iSCSI target/initiator configuration on RHEL7

RHEL: iSCSI target/initiator configuration on RHEL7

# Tested on RHEL 7


# iSCSI target configuration
# ------------------------------------------------------------------------------------------

# Install required package: targetcli

yum install -y targetcli

# and enable the target service on startup

systemctl enable target


# To create an iSCSI target, we'll use 'targetcli', tool for administering targets:

targetcli
   targetcli shell version 2.1.fb41
   Copyright 2011-2013 by Datera, Inc and others.
   For help on commands, type 'help'.

   />

# As backstore, the exported SCSI device, we may choose between "fileio", a file treated
# as a disk image, "block", a local disk block device such as a LVM logical volume or a
# physical device (HDD, DVD, etc), "pscsi" , a local SCSI device of any type, and "ramdisk",
# shared kernel memory. For test purposes, we could also use "nullio" mode, which is not
# backed by any storage and discards all writes, and returns all-zeroes for reads.

# To simplify things, I'll use a fileio device.

# Fileio storage can support either 'write_back' or 'write_thru' operation. The 'write_back'
# enables the local file system cache. This improves performance but increases the risk of
# data loss. It is recommended to use 'write_back=false' to disable 'write_back' in favor
# of 'write_thru'.

# I'll create my fileio backstore, "sharedLUN", of 512M.

/> /backstores/fileio/ create sharedLUN /myluns/sharedLUN.img 512M write_back=false
   Created fileio sharedLUN with size 536870912

# To create a block backstore, use a command like following one:
# /> /backstores/block create name=block_backend dev=[/dev/sdc|/dev/iscsivg/lv_iscsi]
# Note that block backstores usually provide the best performance.


# Then, I create an IQN (Iscsi Qualified Name) called iqn.2016-02.com.example.myserver with
# a target named "myiscsi" and get an associated TPG (Target Portal Group):

/> /iscsi/ create iqn.2016-02.com.example.myserver:myiscsi
   Created target iqn.2016-02.com.example.myserver:myiscsi.
   Created TPG 1.
   Global pref auto_add_default_portal=true
   Created default portal listening on all IPs (0.0.0.0), port 3260.

/> cd /iscsi/iqn.2016-02.com.example.myserver:myiscsi/tpg1
   /iscsi/iqn.20...:myiscsi/tpg1> ls
      o- tpg1 ..................................................... [no-gen-acls, no-auth]
        o- acls ................................................................ [ACLs: 0]
        o- luns ................................................................ [LUNs: 0]
        o- portals .......................................................... [Portals: 0]


# Depending on the RHEL 7 version it may be that a default portal is automatically created
# by the "/iscsi/ create" command. If it is not the case, let's create one. For that we
# have two options: create a default portal, or create a portal specifying what IP address
# to listen to. Creating a default portal uses the default iSCSI port 3260 and allows the
# target to listen on all IP addresses on that port.

# I'll create a default portal

/iscsi/iqn.20...:myiscsi/tpg1> portals/ create
   Using default IP port 3260
   Binding to INADDR_ANY (0.0.0.0)
   Created network portal 0.0.0.0:3260

# Otherwise, to create a portal specifying what IP address to listen to, use this:

# /iscsi/iqn.20...:myiscsi/tpg1> portals/ create 192.168.54.113
#   Using default IP port 3260
#   Created network portal 192.168.54.113:3260


# Now, create a lun. Depending on the kind of backstore previously chosen:

/iscsi/iqn.20...:myiscsi/tpg1> luns/ create /backstores/fileio/sharedLUN
   Created LUN 0.

# For the block backstore shown here above
# /iscsi/iqn.20...:myiscsi/tpg1> luns/ create /backstores/block/block_backend


# Finally, create an acl and an identifier

/iscsi/iqn.20...:myiscsi/tpg1> acls/ create iqn.2016-02.com.example.myserver:client
   Created Node ACL for iqn.2016-02.com.example.myserver:client
   Created mapped LUN 0.

/iscsi/iqn.20...:myiscsi/tpg1> cd acls/iqn.2016-02.com.example.myserver:client/

/iscsi/iqn.20...server:client> set auth userid=myuser
   Parameter userid is now 'myuser'.

/iscsi/iqn.20...server:client> set auth password=mypassword
   Parameter password is now 'mypassword'.

/iscsi/iqn.20...server:client> cd ../..

/iscsi/iqn.20...:myiscsi/tpg1> ls
   o- tpg1 ................................................................... [no-gen-acls, no-auth]
     o- acls .............................................................................. [ACLs: 1]
     | o- iqn.2016-02.com.example.myserver:client .................................. [Mapped LUNs: 1]
     |   o- mapped_lun0 ................................................ [lun0 fileio/sharedLUN (rw)]
     o- luns .............................................................................. [LUNs: 1]
     | o- lun0 ........................................... [fileio/sharedLUN (/myluns/sharedLUN.img)]
     o- portals ........................................................................ [Portals: 1]
       o- 0.0.0.0:3260 ......................................................................... [OK]


# We're done. On exit is automatically saved to /etc/target/saveconfig.json file

/iscsi/iqn.20...:myiscsi/tpg1> exit
   Global pref auto_save_on_exit=true
   Last 10 configs saved in /etc/target/backup.
   Configuration saved to /etc/target/saveconfig.json


# Out iSCSI target is ready to be used.


# If you ever want to clean the entire current local configuration, you can do it by running
# targetcli command like this:

# targetcli clearconfig confirm=true
     All configuration cleared





# iSCSI initiator configuration
# ------------------------------------------------------------------------------------------

# Install required package: iscsi-initiator-utils

yum install -y iscsi-initiator-utils


# Edit /etc/iscsi/initiatorname.iscsi file and replace default content with the initiator
# name configured as acl on target side:

vi /etc/iscsi/initiatorname.iscsi
   InitiatorName=iqn.2016-02.com.example.myserver:client


# If userid and a password have been configured on the server, edit /etc/iscsi/iscsid.conf
# and uncomment/modify following lines

vi /etc/iscsi/iscsid.conf
   node.session.auth.authmethod = CHAP
   node.session.auth.username = myuser
   node.session.auth.password = mypassword


# In RHEL 7, the iSCSI service is lazily started by default. That is, should an iscsiadm
# command be issued the service will start.

# Discover the target

iscsiadm --mode discovery --type sendtargets --portal 192.168.54.113
   192.168.54.113:3260,1 iqn.2016-02.com.example.myserver:myiscsi


# Log in to the target

iscsiadm --mode node --targetname iqn.2016-02.com.example.myserver:myiscsi --portal 192.168.54.113 --login
   Logging in to [iface: default, target: iqn.2016-02.com.example.myserver:myiscsi, portal: 192.168.54.113,3260] (multiple)
   Login to [iface: default, target: iqn.2016-02.com.example.myserver:myiscsi, portal: 192.168.54.113,3260] successful.


# Check the newly discovered target

lsblk --scsi
   NAME HCTL       TYPE VENDOR   MODEL             REV TRAN
   sda  1:0:0:0    disk ATA      ST3160815A       D    ata
   sdb  1:0:1:0    disk ATA      ST3160021A       8.01 ata
   sdc  3:0:0:0    disk ATA      ST3160215ACE     G    ata
   sdd  8:0:0:0    disk LIO-ORG  sharedLUN       4.0  iscsi
   sr0  3:0:1:0    rom  HL-DT-ST DVDRAM GSA-4120B A102 ata

lsblk | egrep "NAME|sdd"
   NAME                MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
   sdd                   8:48   0   512M  0 disk


# Now we are ready to start working with the target. For instance:

mkfs.ext4 /dev/sdd
[...]

blkid /dev/sdd
   /dev/sdd: UUID="35968eb6-b024-485b-a859-71475285c39b" TYPE="ext4"


# If you are planning to persistently mount target, add a line like this to /etc/fstab:
   UUID=35968eb6-b024-485b-a859-71475285c39b    /mnt      ext4     _netdev    0 0


# Display initiator configuration

iscsiadm -m session -P 3
   iSCSI Transport Class version 2.0-870
   version 6.2.0.873-30
   Target: iqn.2016-02.com.example.myserver:myiscsi (non-flash)
        Current Portal: 192.168.54.113:3260,1
        Persistent Portal: 192.168.54.113:3260,1
                **********
                Interface:
                **********
                Iface Name: default
                Iface Transport: tcp
                Iface Initiatorname: iqn.2016-02.com.example.myserver:client
                Iface IPaddress: 192.168.54.113
                Iface HWaddress: <empty>
                Iface Netdev: <empty>
                SID: 1
                iSCSI Connection State: LOGGED IN
                iSCSI Session State: LOGGED_IN
                Internal iscsid Session State: NO CHANGE
                *********
                Timeouts:
                *********
                Recovery Timeout: 120
                Target Reset Timeout: 30
                LUN Reset Timeout: 30
                Abort Timeout: 15
                *****
                CHAP:
                *****
                username: myuser
                password: ********
                username_in: <empty>
                password_in: ********
                ************************
                Negotiated iSCSI params:
                ************************
                HeaderDigest: None
                DataDigest: None
                MaxRecvDataSegmentLength: 262144
                MaxXmitDataSegmentLength: 262144
                FirstBurstLength: 65536
                MaxBurstLength: 262144
                ImmediateData: Yes
                InitialR2T: Yes
                MaxOutstandingR2T: 1
                ************************
                Attached SCSI devices:
                ************************
                Host Number: 8  State: running
                scsi8 Channel 00 Id 0 Lun: 0
                        Attached scsi disk sdd          State: running
0 (0)
Article Rating (No Votes)
Rate this article
Attachments
There are no attachments for this article.
Comments
There are no comments for this article. Be the first to post a comment.
Full Name
Email Address
Security Code Security Code
Related Articles RSS Feed
Linux Cluster Tutorial
Viewed 2080 times since Sat, Sep 29, 2018
Top 10 darmowych i publicznych serwerów DNS
Viewed 2303 times since Tue, May 22, 2018
6 rsync Examples to Exclude Multiple Files and Directories using exclude-from
Viewed 4824 times since Wed, Oct 31, 2018
How to find the largest files and directories in Linux?
Viewed 3239 times since Sun, May 20, 2018
Find All Large Files On A Linux System
Viewed 2108 times since Mon, Oct 29, 2018
red hat 7 tmpfiles service
Viewed 1763 times since Thu, Oct 11, 2018
RHCS6: Extend an existing Logical Volume / GFS2 filesystem
Viewed 3182 times since Sun, Jun 3, 2018
How log rotation works with logrotate
Viewed 4830 times since Fri, Nov 30, 2018
Linux - How to get IP and MAC address of ethernet adapter in Linux
Viewed 2662 times since Fri, Jun 8, 2018
Linux - How to get network speed and statistic of ethernet adapter in Linux
Viewed 2092 times since Fri, Jun 8, 2018