iSCSI Creation, discovery, log-in Configuration of target and initiator

1. iSCSI
Internet Small Computer System Interface

2. iSCSI
• iSCSI is a TCP/IP based protocol for sending
SCSI commands over IP based networks.
• This allows iSCSI infrastructure to extend
beyond a local LAN, and be used on a WAN or
even over the internet.

3. iSCSI

4. Benefits
• Low cost – iSCSI uses the existing network
infrastructure so there is no need to buy
expensive equipment.
• Easy installation and maintenance of iSCSI
SANs – commonly used TCP/IP network
protocols require less IT expertise. Therefore,
no special training is required for network
administrators.

5. Benefits
• Excellent performance – it is a very good alternative to
the more expensive Fibre Channel technology.
• No distance limitation – using IP networking solves the
problem with data replication to remote sites.
• Interoperability and flexibility – iSCSI uses standard
Ethernet switches so there is no need to install special
cabling and switches required with Fibre Channel, it can
also run at different Ethernet speed.

6. Benefits
• Compatibility – It is compatible with many
commonly used standards, respected and
recognized by the Internet Engineering Task Force
(IETF).
• Multipathing – iSCSI supports Multipathing to
improve network resiliency.
• Security – iSCSI offers security features such as
Challenge Handshake Authentication Protocol (2-
way CHAP) and Internet Protocol Security (IPsec).

7. iSCSI SANs are especially recommended
to organizations:
• with limited budget and IT infrastructure,
• spread across several physical locations and
willing to consolidate their storage resources,
• requiring remote data replication and disaster
recovery,
• needing immediate and fast access to data
and backup sets,

8. iSCSI SANs are especially recommended
to organizations:
• working as Application Service Providers
(ASPs), Internet Service Providers (ISPs) or
Storage Service Providers (SSPs),
• utilizing demanding server Virtualization
projects requiring network storage solutions.

9. Key iSCSI Terms
• IQN: iSCSI Qualified Names are used to identify both
targets and initiators.
• Target: Storage resource on an iSCSI server.
• Initiator: A Client is called an initiator.
• Node: A single iSCSI target or initiator.
• Portal: A portal is an IP address on a target or initiator.

10. Steps: Creating an iSCSI volume
Step 1: Create LVM Drive for LUNs (Logical Unit
Number)
Step 2: Create Logical Volumes for LUNs
Step 3: Define LUNs in Target Server

11. Commands to Create LVM Drive
Check the drive first:
# fdisk -l /dev/vda
Now, Create partition on that drive:
# fdisk -cu /dev/vda
• The option ‘-c‘ switch off the DOS compatible
mode.
• The option ‘-u‘ is used to listing partition tables,
give sizes in sectors instead of cylinders.

12. Commands to Create LVM Drive
# fdisk -cu /dev/vda
Choose n to create a New Partition:
Command (m for help): n
Choose p to create a Primary partition:
Command action
e extended
p primary partition (1-4): p

13. Commands to Create LVM Drive
Give a Partition number which you need to
create:
Partition number (1-4): 1
Define the size of that partition, use the default
settings to use full size of Drive.
Choose the type of partition:
Command (m for help): t

14. Commands to Create LVM Drive
Choose which partition want to change the type:
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)
Check the changes by print (p) option to list the
partition table
Command (m for help): p
Write the changes using w to exit from fdisk

15. Commands to Create LVM Drive
• Reboot the system and list the Partition table
using the following fdisk command.
# fdisk -l /dev/vda

16. Commands to Create Logical Volumes
• Create Physical volume:
# pvcreate /dev/vda1
• Create a Volume group with name of iSCSI to
identify the group:
# vgcreate testvg /dev/vda1
• List volume group using vgs or vgdisplay:
#vgs testvg

17. Commands to Create Logical Volumes
• Create one or more Logical volumes:
# lvcreate -L 8G -n lv1 testvg
# lvcreate -L 8G -n lv2 testvg
• List the Physical volume, Volume group, logical
volumes to confirm:
# pvs && vgs && lvs
# lvs

18. Commands to Define LUNs in Target Server
• Install the package scsi-target-utils:
# yum –y install scsi-target-utils
• Start the service
# service tgtd start; chkconfig tgtd on
• Open and edit Target configuration file
‘/etc/tgt/targets.conf’

19. Commands to Define LUNs in Target Server
• Append the following volume definition in target
conf file.
iSCSI qualified name
2 LVs Shared for particular LUN.
Example:
<target iqn.2014-07.com.test:tgt1>
backing-store /dev/testvg/lv1
</target>
• Save and close the file

20. Commands to Define LUNs in Target Server
• Reload the configuration by starting tgd service
# /etc/init.d/tgtd reload
• Verify the available LUNs
# tgtadm --mode target --op show

21. Configure an iSCSI Initiator
• Install the package iscsi-initiator-utils:
# yum –y install scsi-initiator-utils
• Change the initiator name in the following file:
‘/etc/iscsi/initiatorname.iscsi’
• Start the service
# service iscsi start; chkconfig iscsi on

22. Discover the target
Use the iscsiadm command to start the iSCSI
discovery:
# iscsiadm -m discovery -t st -p 192.168.0.10
To show the Information about target:
# iscsiadm -m node

23. Log in to the target
Use the iscsiadm command to log in to
discovered iSCSI target:
# iscsiadm -m node –T <IQN name> -p 192.168.0.10 -l
• To stop using target:
# iscsiadm -m node –T <IQN name> -p 192.168.0.10 –u
To delete all information about a target:
# iscsiadm -m node –T <IQN name> -p 192.168.0.10 –op delete

24. List the iSCSI drives
• By Path
# ls –la /dev/disk/by-path
• By id
# ls –la /dev/disk/by-path