iSCSI Target and Initiator configuration
Summary:
In this article we will see about how to configure RedHat server as iSCSI Target and iSCSI Initiator.
iSCSI Target (Server) configuration
[root@iscsi-target yum.repos.d]# cat /etc/tgt/targets.conf
default-driver iscsi
<target iqn.2014-04.com.example:iscsi-target:storage>
backing-store /dev/vg_iscsidisk/lv_lun1
</target>
Restart the tgtd service and make it persistent after reboot.
[root@iscsi-target yum.repos.d]# /etc/init.d/tgtd restart
Stopping SCSI target daemon: [ OK ]
Starting SCSI target daemon: [ OK ]
[root@iscsi-target yum.repos.d]# chkconfig tgtd on
Listing the Lun details.
[root@iscsi-target yum.repos.d]# tgt-admin -s
Target 1: iqn.2014-04.com.example:iscsi-target:storage
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
Backing store type: null
Backing store path: None
Backing store flags:
LUN: 1
Type: disk
SCSI ID: IET 00010001
SCSI SN: beaf11
Size: 4295 MB, Block size: 512
Online: Yes
Removable media: No
Prevent removal: No
Readonly: No
Backing store type: rdwr
Backing store path: /dev/vg_iscsidisk/lv_lun1
Backing store flags:
Account information:
ACL information:
ALL
iSCSI Initiator (Client) Configuration
- Installing the required package for initiator
[root@iscsi-initiator ~]# yum groupinstall "iSCSI Storage Client"
......
Resolving Dependencies
--> Running transaction check
---> Package iscsi-initiator-utils.x86_64 0:6.2.0.872-41.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
================================================================================
Package Arch Version Repository Size
================================================================================
Installing:
iscsi-initiator-utils x86_64 6.2.0.872-41.el6 RHEL-CD 654 k
Transaction Summary
================================================================================
Install 1 Package(s)
Total download size: 654 k
Installed size: 2.2 M
Is this ok [y/N]: y
iSCSI Qualified Name (IQN) configuration
[root@iscsi-initiator ~]# cat /etc/iscsi/initiatorname.iscsi
InitiatorName=iqn.2014-04.com.example:iscsi-initiator
iSCSI initiator consist of 2 services iscsi and iscsid. We will start the service and make it persistent.
[root@iscsi-initiator ~]# service iscsi restart
Stopping iscsi: [ OK ]
[root@iscsi-initiator ~]# service iscsid restart
Stopping iscsid:
Starting iscsid: [ OK ]
[root@iscsi-initiator ~]# chkconfig iscsi on
[root@iscsi-initiator ~]# chkconfig iscsid on
Discovering the the presented LUN using iscsiadm command.
[root@iscsi-initiator ~]# iscsiadm -m discovery -t sendtargets -p 192.168.122.101
192.168.122.101:3260,1 iqn.2014-04.com.example:iscsi-target:storage
Login to the lun. Once you login you can see the disk in "fdisk -l" command
[root@iscsi-initiator ~]# iscsiadm --mode node --targetname iqn.2014-04.com.example:iscsi-target:storage --portal 192.168.122.101:3260 --login
Logging in to [iface: default, target: iqn.2014-04.com.example:iscsi-target:storage, portal: 192.168.122.101,3260] (multiple)
Login to [iface: default, target: iqn.2014-04.com.example:iscsi-target:storage, portal: 192.168.122.101,3260] successful.
Seeing the newly discovered LUN details in "fdis-l -l" command
[root@iscsi-initiator ~]# fdisk -l
Disk /dev/vda: 8589 MB, 8589934592 bytes
16 heads, 63 sectors/track, 16644 cylinders
Units = cylinders of 1008 * 512 = 516096 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0004fd53
Device Boot Start End Blocks Id System
/dev/vda1 * 3 1017 512000 83 Linux
/dev/vda2 1018 16645 7875584 8e Linux LVM
Disk /dev/sda: 4294 MB, 4294967296 bytes
133 heads, 62 sectors/track, 1017 cylinders
Units = cylinders of 8246 * 512 = 4221952 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000
Now we can create a partition and use it as normal disk
[root@iscsi-initiator ~]# fdisk /dev/sda
Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
Building a new DOS disklabel with disk identifier 0x305c97fa.
Changes will remain in memory only, until you decide to write them.
After that, of course, the previous content won't be recoverable.
Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)
WARNING: DOS-compatible mode is deprecated. It's strongly recommended to
switch off the mode (command 'c') and change display units to
sectors (command 'u').
Command (m for help): n
Command action
e extended
p primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-1017, default 1):
Using default value 1
Last cylinder, +cylinders or +size{K,M,G} (1-1017, default 1017):
Using default value 1017
Command (m for help): p
Disk /dev/sda: 4294 MB, 4294967296 bytes
133 heads, 62 sectors/track, 1017 cylinders
Units = cylinders of 8246 * 512 = 4221952 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x305c97fa
Device Boot Start End Blocks Id System
/dev/sda1 1 1017 4193060 83 Linux
Command (m for help): w
The partition table has been altered!
Calling ioctl() to re-read partition table.
Syncing disks.
[root@iscsi-initiator ~]# partprobe /dev/sda
[root@iscsi-initiator ~]# pvcreate /dev/sda1
Writing physical volume data to disk "/dev/sda1"
Physical volume "/dev/sda1" successfully created
[root@iscsi-initiator ~]# vgcreate vg_iscsi /dev/sda1
Volume group "vg_iscsi" successfully created
[root@iscsi-initiator ~]# lvcreate -l 100%FREE -n lv_lun1 vg_iscsi
Logical volume "lv_lun1" created
[root@iscsi-initiator ~]# vgs
VG #PV #LV #SN Attr VSize VFree
vg_iscsi 1 1 0 wz--n- 4.00g 0
vg_iscsiinitiator 1 2 0 wz--n- 7.51g 0
[root@iscsi-initiator ~]# lvs
LV VG Attr LSize Pool Origin Data% Move Log Copy% Convert
lv_lun1 vg_iscsi -wi-a--- 4.00g
lv_root vg_iscsiinitiator -wi-ao-- 5.54g
lv_swap vg_iscsiinitiator -wi-ao-- 1.97g
[root@iscsi-initiator ~]# mkfs.ext3 /dev/vg_iscsi/lv_lun1
Adding fstab entry. _netdev option is important.If you donot provide that we will have issue when we reboot the system. Provide UUID instead of device file name
[root@iscsi-initiator ~]# blkid /dev/vg_iscsi/lv_lun1
/dev/vg_iscsi/lv_lun1: UUID="f9b2d5e1-f10b-4aa2-9367-64cda002bbc7" TYPE="ext3"
[root@iscsi-initiator ~]# cat /etc/fstab | grep net
UUID=f9b2d5e1-f10b-4aa2-9367-64cda002bbc7 /iscsi ext3 _netdev 0 0
[root@iscsi-initiator ~]# mkdir /iscsi
[root@iscsi-initiator ~]# mount /iscsi
[root@iscsi-initiator ~]# df -hT /iscsi
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/vg_iscsi-lv_lun1
ext3 4.0G 73M 3.7G 2% /iscsi
You can use iscsiadm command to find which disk is iSCSI disk.
[root@iscsi-initiator ~]# iscsiadm -m session -P 3 | grep Atta
Attached SCSI devices:
Attached scsi disk sda State: running
Now we completed the iSCSI Initiator configuration.
Removing iSCSI Disk
Now we will see how to Delete or remove the iSCSI disk from the Initiator.
- Disable or logout from an iSCSI Target.
[root@iscsi-initiator ~]# iscsiadm -m node -T iqn.2014-04.com.example:iscsi-target:storage --portal 192.168.122.101:3260 --logout
Logging out of session [sid: 4, target: iqn.2014-04.com.example:iscsi-target:storage, portal: 192.168.122.101,3260]
Logout of [sid: 4, target: iqn.2014-04.com.example:iscsi-target:storage, portal: 192.168.122.101,3260] successful.Delete the target record
Delete the iSCSI target record
[root@iscsi-initiator ~]# iscsiadm -m node -o delete -T iqn.2014-04.com.example:iscsi-target:storage --portal 192.168.122.101:3260
Stop the iscsi and iscsid service.
[root@iscsi-initiator ~]# chkconfig iscsi off
[root@iscsi-initiator ~]# chkconfig iscsid off
[root@iscsi-initiator ~]# service iscsi stop
Stopping iscsi: [ OK ]
[root@iscsi-initiator ~]# service iscsid stop
Stopping iscsid: [ OK ]
