iSCSI Server installation Providing Remote block storage

iSCSI Server installation and configuration RHEL7 Providing Remote Block Storage

iSCSI means Internet Small SCSI System Interface, We will use iSCSI connectivity because it is cost effective compare to FC connection. Fibre Connection required separate Hardware such as like FC switch (SAN Switch) FC switch is more cost compare to normal network switch. To provide iSCSI based storage we do not required any extra environment because we can make use of existing Network switches. Let’s see how this technology is going to work for us iscsi server installation and configuration RHEL 7 providing remote block storage.

We have different types of storage’s such as

  1. DAS – Directly attache storage
  2. NAS – Network Attached Storage
  3. SAN – Storage Area Network

iSCSI protocol comes under SAN (Storage Area Network) To allocate remote block storage to clients below are the steps we have to follow

  1. Create one Partition
  2. Create LVM using that partition (Don’t format)
  3. Install iSCSI Utilities if not available
  4. Create LUN and Map to iSCSI client
  5. iSCSI server = Target. iSCSI Client = Initiator.

Let’s see below is the process of creating and mapping the iSCSI LUN from iSCSI server to Client.

Environment

Server IP =192.168.4.27

Client IP = 192.168.4.13

By Installing and configuring this iSCSI Server, We are Turing Linux box as SAN.  

Creating Partition

Here i have new HDD called /dev/sdb 10GB with no partitions

[root@iSCSIServer ~]# fdisk -l /dev/sdb

Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 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: 0xea9e3f19

Device Boot Start End Blocks Id System

Standard partition creation and converting standard to LVM

[root@iSCSIServer ~]# 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.


Command (m for help): n
Partition type:
 p primary (0 primary, 0 extended, 4 free)
 e extended
Select (default p):
Using default response p
Partition number (1-4, default 1):
First sector (2048-20971519, default 2048): 
Using default value 2048
Last sector, +sectors or +size{K,M,G} (2048-20971519, default 20971519): +2G
Partition 1 of type Linux and of size 2 GiB is set

Command (m for help): p

Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 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: 0xea9e3f19

Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 83 Linux

Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'

Command (m for help): p

Disk /dev/sdb: 10.7 GB, 10737418240 bytes, 20971520 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: 0xea9e3f19

Device Boot Start End Blocks Id System
/dev/sdb1 2048 4196351 2097152 8e Linux LVM

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

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

Update to Kernel when we create new partition, partition table should be up-to date other wise partition will not be listed, use below command to update

[root@iSCSIServer ~]# partprobe /dev/sdb

Creating Physical Volume, Volume Group and Logical Volume

[root@iSCSIServer ~]# pvcreate /dev/sdb1
 Physical volume "/dev/sdb1" successfully created

[root@iSCSIServer ~]# vgcreate VG0 /dev/sdb1
 Volume group "VG0" successfully created
[root@iSCSIServer ~]# vgs
 VG #PV #LV #SN Attr VSize VFree
 VG0 1 0 0 wz--n- 2.00g 2.00g
 rhel 1 2 0 wz--n- 39.51g 44.00m

[root@iSCSIServer ~]# lvcreate -l 100%FREE -n iscsilv VG0
WARNING: ext4 signature detected on /dev/VG0/iscsilv at offset 1080. Wipe it? [y/n]: y
 Wiping ext4 signature on /dev/VG0/iscsilv.
 Logical volume "iscsilv" created.

iSCSI Server Installation Providing Remote block storage

As per above output we just created Logical Volume but we did no formatted, Means we did not created any file system in it.

[root@iSCSIServer ~]# yum install targetcli*

Installed:
 targetcli.noarch 0:2.1.fb37-3.el7

Dependency Installed:
 pyparsing.noarch 0:1.5.6-9.el7 python-configshell.noarch 1:1.1.fb14-1.el7 python-kmod.x86_64 0:0.9-4.el7 python-rtslib.noarch 0:2.1.fb50-1.el7 python-urwid.x86_64 0:1.1.1-3.el7

Complete!

Targetcli is the command to enter into iscsi console

targetcli command

targetcli command

Create Storage Object and Create IQN (iSCSI Qualified Name) to map LUN. This IQN we should take from iSCSI client machine, either we can create our own.

/> /backstores/block create LUN /dev/VG0/iscsilv

/> /iscsi create iqn.2017-03.com.arkit:iSCSIClient1
Creating Storage Object

Creating Storage Object

Go to iSCSI Client Side

Client side we have to install iscsi utilities to connect iscsi server. 

Install iscsi-initiator-utils-iscsiuio-6.2.0.873-29.el7.x86_64 rpm in iSCSI client

[root@iSCSIClient ~]# yum install iscsi*

Get IQN number from Client machine and add to server for mapping disk from server.

[root@iSCSIClient ~]# cat /etc/iscsi/initiatorname.iscsi
InitiatorName=iqn.1994-05.com.redhat:ba1abe3b1a4

Enable and Start iscsid service

[root@iSCSIClient ~]# systemctl enable iscsid.service
ln -s '/usr/lib/systemd/system/iscsid.service' '/etc/systemd/system/multi-user.target.wants/iscsid.service'
[root@iSCSIClient ~]# systemctl start iscsid.service

[root@iSCSIClient ~]# systemctl status iscsid.service
iscsid.service - Open-iSCSI
 Loaded: loaded (/usr/lib/systemd/system/iscsid.service; enabled)
 Active: active (running) since Sun 2016-10-23 19:19:49 IST; 11s ago
 Docs: man:iscsid(8)
 man:iscsiadm(8)
 Process: 4144 ExecStart=/usr/sbin/iscsid (code=exited, status=0/SUCCESS)
 Main PID: 4146 (iscsid)
 CGroup: /system.slice/iscsid.service
 ├─4145 /usr/sbin/iscsid
 └─4146 /usr/sbin/iscsid

Oct 23 19:19:49 iSCSIClient iscsid[4145]: iSCSI daemon with pid=4146 started!
Oct 23 19:19:49 iSCSIClient systemd[1]: Started Open-iSCSI.

Come Back to iSCSI Server side

Now add client IQN in server so that we can map LUN

/> /iscsi create iqn.1994-05.com.redhat:ba1abe3b1a4
Created target iqn.1994-05.com.redhat:ba1abe3b1a4.
Created TPG 1.
Global pref auto_add_default_portal=true
Created default portal listening on all IPs (0.0.0.0), port 3260.
/> /iscsi/iqn.1994-05.com.redhat:ba1abe3b1a4/tpg1/acls create iqn.1994-05.com.redhat:ba1abe3b1a4
Created Node ACL for iqn.1994-05.com.redhat:ba1abe3b1a4

Create New LUN using existing LVM and map to client

/> /iscsi/iqn.1994-05.com.redhat:ba1abe3b1a4/tpg1/luns create /backstores/block/LUN
Created LUN 0.
Created LUN 0->0 mapping in node ACL iqn.1994-05.com.redhat:ba1abe3b1a4

Portal Creation in Server to map

/> /iscsi/iqn.1994-05.com.redhat:ba1abe3b1a4/tpg1/portals create 192.168.4.14
Using default IP port 3260
Could not create NetworkPortal in configFS.

If your able to see above error while creating portal then do delete default port 0.0.0.0 then create new

/> /iscsi/iqn.2017-03.com.arkit:iscsiclient1/tpg1/portals delete 0.0.0.0 ip_port=3260
Deleted network portal 0.0.0.0:3260
/> /iscsi/iqn.1994-05.com.redhat:ba1abe3b1a4/tpg1/portals create 192.168.4.14
Using default IP port 3260
Created network portal 192.168.4.14:3260.

Save the configuration 

/> saveconfig
Last 10 configs saved in /etc/target/backup.
Configuration saved to /etc/target/saveconfig.json

Exit from the Console

/> exit
Global pref auto_save_on_exit=true
Last 10 configs saved in /etc/target/backup.
Configuration saved to /etc/target/saveconfig.json

Allow Firewall Port to communicate with iSCSI Client

3260 iscsi default port 

[root@iSCSIServer ~]# firewall-cmd --permanent --add-port=3260/tcp
success
[root@iSCSIServer ~]# firewall-cmd --permanent --add-port=3260/udp
success
[root@iSCSIServer ~]# firewall-cmd --reload
success

Client Side to connect iSCSI LUN

[root@desktop4 ~]# iscsiadm -m discovery -t st -p 192.168.4.27
192.168.4.27:3260,1 iqn.1994-05.com.redhat:ba1abe3b1a4

[root@desktop4 ~]# iscsiadm -m node -T iqn.1994-05.com.redhat:ba1abe3b1a4 -p 192.168.4.27 -l
Logging in to [iface: default, target: iqn.1994-05.com.redhat:ba1abe3b1a4, portal: 192.168.4.27,3260] (multiple)
Login to [iface: default, target: iqn.1994-05.com.redhat:ba1abe3b1a4, portal: 192.168.4.27,3260] successful.

After successful mapping of LUN now you can create file system on LUN, To Create file system repeat Step 1 (Creating Partition)

[root@iSCSIClient ~]# partprobe /dev/sda
[root@iSCSIClient ~]# mkfs.ext4 /dev/sda1
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=0 blocks, Stripe width=1024 blocks
327680 inodes, 1308672 blocks
65433 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=1340080128
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

[root@iSCSIClient ~]# mkdir /ravi


[root@iSCSIClient ~]# vim /etc/fstab 
[root@iSCSIClient ~]# cat /etc/fstab |grep sda
/dev/sda1 /ravi ext4 _netdev 0 0
[root@iSCSIClient ~]# mount -a
[root@iSCSIClient ~]# df -h |grep ravi
/dev/sda1 2.0G 20M 2.0G 1% /ravi

Enjoy…………….

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ARK

My Name is ARK. Expert in grasping any new technology, Interested in Sharing the knowledge. Learn more & Earn More

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