Thursday, December 24, 2015

ISCSI Server & Client Installation/Configuration on RHEL 5.9 64bits


Table of Contents




Environment Details


Master Server
192.168.144.136         imastiscsi.example.com          mastiscsi
192.168.144.155

Client Server
192.168.144.153         iscsiclient.example.com         iscsiclient
192.168.144.154



Installation of ISCSI Target on Master server


1.             Checking Disk Space
[root@mastiscsi ~]# fdisk -l

Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          32      257008+  83  Linux
/dev/sda2              33        5221    41680642+  8e  Linux LVM

Disk /dev/sdb: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdb doesn't contain a valid partition table


2.             Mount RHEL 5.9 DVD for configuration of Yum Server
[root@mastiscsi ~]# mount /dev/cdrom /mnt/rhel5/
mount: block device /dev/cdrom is write-protected, mounting read-only

[root@mastiscsi ~]# cat /etc/yum.repos.d/rhel5-media.repo
[cd-media]
name=rhel5.9-media
baseurl=file:///mnt/rhel5/Server
gpgcheck=1
enabled=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-redhat-release


3.             Download below rmps and copy into root folder
[root@mastiscsi ~]# ls
      perl-Config-General-2.52-31.1.x86_64.rpm
      scsi-target-utils-1.0.14-2.el5.x86_64.rpm

4.             Install below software & its dependencies

[root@mastiscsi ~]# rpm -ivh perl-Config-General-2.52-31.1.x86_64.rpm
warning: perl-Config-General-2.52-31.1.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID dcef338c
Preparing...                ########################################### [100%]
   1:perl-Config-General    ########################################### [100%]

[root@mastiscsi ~]# yum install libibverbs*
Installed:
  libibverbs.i386 0:1.1.6-3.el5                 libibverbs.x86_64 0:1.1.6-3.el5
  libibverbs-devel.i386 0:1.1.6-3.el5           libibverbs-devel.x86_64 0:1.1.6-3.el5
  libibverbs-static.x86_64 0:1.1.6-3.el5        libibverbs-utils.x86_64 0:1.1.6-3.el5
Dependency Installed:
  libnes.x86_64 0:1.1.3-1.el5                 openib.noarch 0:1.5.4.1-4.el5

[root@mastiscsi ~]# yum install librdmacm*
Installed:
  librdmacm.i386 0:1.0.15-2.el5                 librdmacm.x86_64 0:1.0.15-2.el5
  librdmacm-devel.i386 0:1.0.15-2.el5           librdmacm-devel.x86_64 0:1.0.15-2.el5
  librdmacm-static.x86_64 0:1.0.15-2.el5        librdmacm-utils.x86_64 0:1.0.15-2.el5

[root@mastiscsi ~]# rpm -ivh scsi-target-utils-1.0.14-2.el5.x86_64.rpm
warning: scsi-target-utils-1.0.14-2.el5.x86_64.rpm: Header V3 DSA signature: NOKEY, key ID e8562897
Preparing...                ########################################### [100%]
   1:scsi-target-utils      ########################################### [100%]

5.             Check NetworkManager and off by chkconfig command
[root@mastiscsi ~]# chkconfig --list | grep Netwo
NetworkManager  0:off   1:off   2:off   3:off   4:off   5:off   6:off

6.             Check and start tgtd service
[root@mastiscsi ~]# chkconfig --list | grep tgtd
tgtd            0:off   1:off   2:off   3:off   4:off   5:off   6:off

[root@mastiscsi ~]# service tgtd start
Starting SCSI target daemon: Starting target framework daemon

[root@mastiscsi ~]# chkconfig tgtd on

[root@mastiscsi ~]# chkconfig --list | grep tgt
tgtd            0:off   1:off   2:on    3:on    4:on    5:on    6:off

7.             Take backup of /etc/tgt/targets.conf file and start service
[root@mastiscsi ~]# cp -p /etc/tgt/targets.conf /etc/tgt/targets.conf.bkp

[root@mastiscsi ~]# vi /etc/tgt/targets.conf
<target iqn.2015-08.com.example:mastiscsi.disk1>
    backing-store /dev/sdb
</target>

[root@mastiscsi ~]# service tgtd restart
Stopping SCSI target daemon: Stopping target framework daemon                                                                   [  OK  ]
Starting SCSI target daemon: Starting target framework daemon

8.             Check lun & target details
[root@mastiscsi ~]# tgt-admin -s
Target 1: iqn.2015-08.com.example:mastiscsi.disk1
    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
            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
            Readonly: No
            Backing store type: rdwr
            Backing store path: /dev/sdb
            Backing store flags:
    Account information:
    ACL information:
        ALL
9.             Check & disable iptables & selinux
[root@mastiscsi ~]# service iptables status
Firewall is stopped.

[root@mastiscsi ~]# getenforce
Disabled


  

Installation of ISCSI imitator on Client Server


1.             Check installed iscsi-initiator rpm
[root@iscsiclient ~]# rpm -qa | grep iscsi
iscsi-initiator-utils-6.2.0.872-16.el5

2.             Check & modify initiator name
[root@iscsiclient ~]# cat /etc/iscsi/initiatorname.iscsi
InitiatorName=iqn.2015-08.com.example:mastiscsi
                Above mastiscsi is master server hostname

3.             Start iscsi service and make it permanent
[root@iscsiclient ~]# /etc/init.d/iscsid restart
Stopping iSCSI daemon:                                                      [  OK  ]
Starting iSCSI daemon:                                                        [  OK  ]

[root@iscsiclient ~]# chkconfig --list | grep scsi
iscsi           0:off   1:off   2:off   3:on    4:on    5:on    6:off
iscsid          0:off   1:off   2:off   3:on    4:on    5:on    6:off

4.             Discover iscsi server by two IPs of Master Server
[root@iscsiclient ~]# iscsiadm -m discoverydb -t st --portal 192.168.144.136:3260 --discover
                192.168.144.136:3260,1 iqn.2015-08.com.example:mastiscsi.disk1

[root@iscsiclient ~]# iscsiadm -m discoverydb -t st --portal 192.168.144.155:3260 --discover
                192.168.144.155:3260,1 iqn.2015-08.com.example:mastiscsi.disk1

5.             Login Master server with both IPs
[root@iscsiclient ~]# iscsiadm -m node --portal 192.168.144.136:3260 -T iqn.2015-08.com.example:mastiscsi.disk1 -l
Logging in to [iface: default, target: iqn.2015-08.com.example:mastiscsi.disk1, portal: 192.168.144.136,3260] (multiple)
Login to [iface: default, target: iqn.2015-08.com.example:mastiscsi.disk1, portal: 192.168.144.136,3260] successful.

[root@iscsiclient ~]# iscsiadm -m node --portal 192.168.144.155:3260 -T iqn.2015-08.com.example:mastiscsi.disk1 -l
Logging in to [iface: default, target: iqn.2015-08.com.example:mastiscsi.disk1, portal: 192.168.144.155,3260] (multiple)
Login to [iface: default, target: iqn.2015-08.com.example:mastiscsi.disk1, portal: 192.168.144.155,3260] successful.

6.             Check Disk Space
[root@iscsiclient ~]# fdisk -l
Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          32      257008+  83  Linux
/dev/sda2              33        5221    41680642+  8e  Linux LVM

Disk /dev/sdb: 4294 MB, 4294967296 bytes
133 heads, 62 sectors/track, 1017 cylinders
Units = cylinders of 8246 * 512 = 4221952 bytes

Disk /dev/sdb doesn't contain a valid partition table

Disk /dev/sdc: 4294 MB, 4294967296 bytes
133 heads, 62 sectors/track, 1017 cylinders
Units = cylinders of 8246 * 512 = 4221952 bytes

Disk /dev/sdc doesn't contain a valid partition table



Configuration of multipath on Client


Multipath configuration is required to configure on Client Machine only. It is not require on Master Server
1.             Check below rpms:
[root@iscsiclient ~]# rpm -qa | grep device-mapper
device-mapper-1.02.67-2.el5
device-mapper-multipath-0.4.7-54.el5
device-mapper-event-1.02.67-2.el5
device-mapper-1.02.67-2.el5

2.             Check if kernel is loaded with multipath module
[root@iscsiclient ~]# lsmod | grep multipath
dm_multipath      58969  0
scsi_dh                   42561  1 dm_multipath
dm_mod                102417  15 dm_multipath,dm_raid45,dm_snapshot,dm_zero,dm_mirror,dm_log

3.             Check current mapper device
[root@iscsiclient ~]# ls -l /dev/mapper/
total 0
crw------- 1 root root  10, 60 Aug 27 17:30 control
brw-rw---- 1 root disk 253,  2 Aug 27 17:31 vg0-home
brw-rw---- 1 root disk 253,  0 Aug 27 17:31 vg0-root
brw-rw---- 1 root disk 253,  3 Aug 27 17:30 vg0-swap
brw-rw---- 1 root disk 253,  1 Aug 27 17:31 vg0-var

4.             Comment default blacklist detail
[root@iscsiclient ~]# vi /etc/multipath.conf
#blacklist {
#        devnode "*"
#}

5.             Start multipathd service and make it permanent
[root@iscsiclient ~]# service multipathd start
Starting multipathd daemon:                                             [  OK  ]

[root@iscsiclient ~]# chkconfig multipathd on

6.             Check current multipath details
[root@iscsiclient ~]# multipath -ll
mpath0 (1IET_00010001) dm-4 IET,VIRTUAL-DISK
[size=4.0G][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 31:0:0:1 sdb 8:16  [active][ready]
\_ round-robin 0 [prio=1][enabled]
 \_ 32:0:0:1 sdc 8:32  [active][ready]

7.             Now check Disk Details
[root@iscsiclient ~]# fdisk -l
Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          32      257008+  83  Linux
/dev/sda2              33        5221    41680642+  8e  Linux LVM

Disk /dev/sdb: 4294 MB, 4294967296 bytes
133 heads, 62 sectors/track, 1017 cylinders
Units = cylinders of 8246 * 512 = 4221952 bytes

Disk /dev/sdb doesn't contain a valid partition table

Disk /dev/sdc: 4294 MB, 4294967296 bytes
133 heads, 62 sectors/track, 1017 cylinders
Units = cylinders of 8246 * 512 = 4221952 bytes

Disk /dev/sdc doesn't contain a valid partition table

Disk /dev/dm-4: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/dm-4 doesn't contain a valid partition table

8.             Check new mapper device
[root@iscsiclient ~]# ls -l /dev/mapper/
total 0
crw------- 1 root root  10, 60 Aug 27 17:30 control
brw-rw---- 1 root disk 253,  4 Aug 27 18:17 mpath0
brw-rw---- 1 root disk 253,  2 Aug 27 17:31 vg0-home
brw-rw---- 1 root disk 253,  0 Aug 27 17:31 vg0-root
brw-rw---- 1 root disk 253,  3 Aug 27 17:30 vg0-swap
brw-rw---- 1 root disk 253,  1 Aug 27 17:31 vg0-var

9.             Format new Disk
[root@iscsiclient ~]# fdisk /dev/mapper/mpath0
Command (m for help): p
Disk /dev/mapper/mpath0: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-522, default 1): <Enter>
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-522, default 522): <Enter>
Using default value 522

Command (m for help): p
Disk /dev/mapper/mpath0: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath0p1               1         522     4192933+  83  Linux

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): p
Disk /dev/mapper/mpath0: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath0p1               1         522     4192933+  8e  Linux LVM

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

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.

10.          Check & make new partition kernel readable
[root@iscsiclient ~]# fdisk -l /dev/mapper/mpath0
Disk /dev/mapper/mpath0: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath0p1               1         522     4192933+  8e  Linux LVM

[root@iscsiclient ~]# partprobe  /dev/mapper/mpath0

[root@iscsiclient ~]# fdisk -l
Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          32      257008+  83  Linux
/dev/sda2              33        5221    41680642+  8e  Linux LVM

Disk /dev/sdb: 4294 MB, 4294967296 bytes
133 heads, 62 sectors/track, 1017 cylinders
Units = cylinders of 8246 * 512 = 4221952 bytes

Disk /dev/sdb doesn't contain a valid partition table

Disk /dev/sdc: 4294 MB, 4294967296 bytes
133 heads, 62 sectors/track, 1017 cylinders
Units = cylinders of 8246 * 512 = 4221952 bytes

Disk /dev/sdc doesn't contain a valid partition table

Disk /dev/dm-4: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot      Start         End      Blocks   Id  System
/dev/dm-4p1               1         522     4192933+  8e  Linux LVM

11.          New partition is now visible on reaming disks as per above output so it is require to reboot machine
[root@iscsiclient ~]# reboot

Broadcast message from root (pts/0) (Thu Aug 27 19:01:54 2015):

The system is going down for reboot NOW!
[root@iscsiclient ~]#

12.          After reboot the machine now new partition is visible on remaining disk
[root@iscsiclient ~]# fdisk -l

Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          32      257008+  83  Linux
/dev/sda2              33        5221    41680642+  8e  Linux LVM

Disk /dev/sdb: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         522     4192933+  8e  Linux LVM

Disk /dev/sdc: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1         522     4192933+  8e  Linux LVM

Disk /dev/dm-4: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot      Start         End      Blocks   Id  System
/dev/dm-4p1               1         522     4192933+  8e  Linux LVM

Disk /dev/dm-5: 4293 MB, 4293563904 bytes
255 heads, 63 sectors/track, 521 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/dm-5 doesn't contain a valid partition table

Note: After reboot machine above /dev/dm-5 has additionally added. But it is useless.



Creating pv, vg & lvm


1.             We should not create physical volume with /dev/dm-4p1. It will show error like below
[root@iscsiclient ~]# pvcreate /dev/dm-4p1 -t                                                                            
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
  Device /dev/dm-4p1 not found (or ignored by filtering).

Note : Also not create Physical volume with /dev/sdb1 and /dev/sdc1

2.             List current Device
[root@iscsiclient ~]# ls -l /dev/mapper/
total 0
crw------- 1 root root  10, 60 Aug 27 19:03 control
brw-rw---- 1 root disk 253,  4 Aug 27 19:04 mpath0
brw-rw---- 1 root disk 253,  5 Aug 27 19:04 mpath0p1
brw-rw---- 1 root disk 253,  2 Aug 27 19:03 vg0-home
brw-rw---- 1 root disk 253,  0 Aug 27 19:03 vg0-root
brw-rw---- 1 root disk 253,  3 Aug 27 19:03 vg0-swap
brw-rw---- 1 root disk 253,  1 Aug 27 19:03 vg0-var

3.             Now Create Physical Volume
[root@iscsiclient ~]# pvcreate /dev/mapper/mpath0p1
  Writing physical volume data to disk "/dev/mapper/mpath0p1"
  Physical volume "/dev/mapper/mpath0p1" successfully created

[root@iscsiclient ~]# pvdisplay /dev/mpath/mpath0p1
  "/dev/mpath/mpath0p1" is a new physical volume of "4.00 GB"
  --- NEW Physical volume ---
  PV Name               /dev/mpath/mpath0p1
  VG Name
  PV Size               4.00 GB
  Allocatable           NO
  PE Size (KByte)       0
  Total PE              0
  Free PE               0
  Allocated PE          0
  PV UUID               TLgOgU-8PF6-8x95-3Yqv-vVc2-6soy-wSuEkc

4.             Create Volume Group
[root@iscsiclient ~]# vgcreate wasvg /dev/mpath/mpath0p1
  Volume group "wasvg" successfully created

[root@iscsiclient ~]# vgdisplay wasvg
  --- Volume group ---
  VG Name               wasvg
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  1
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                0
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               4.00 GB
  PE Size               4.00 MB
  Total PE              1023
  Alloc PE / Size       0 / 0
  Free  PE / Size       1023 / 4.00 GB
  VG UUID               VigepC-As6r-9q1d-NLlv-gMiK-hJr9-kGNFFt

5.             Create Logical Volume
[root@iscsiclient ~]# lvcreate -L 4GB -n wasvg-datalv wasvg -t
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
  Volume group "wasvg" has insufficient free space (1023 extents): 1024 required.

[root@iscsiclient ~]# lvcreate -L 3GB -n wasvg-datalv wasvg
  Logical volume "wasvg-datalv" created

[root@iscsiclient ~]# lvdisplay /dev/wasvg/wasvg-datalv
  --- Logical volume ---
  LV Name                /dev/wasvg/wasvg-datalv
  VG Name                wasvg
  LV UUID                aaT8Df-2U6T-Eh98-YLks-Q1YI-EWQN-oaF6lf
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                3.00 GB
  Current LE             768
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:6


Adding 5GB Disk Space on master & Configure as target server


1.             Check disk space before scanning new disk without reboot the machine
[root@mastiscsi ~]# fdisk -l
Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          32      257008+  83  Linux
/dev/sda2              33        5221    41680642+  8e  Linux LVM

Disk /dev/sdb: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         522     4192933+  8e  Linux LVM


2.             Scan new Disk on Master Server and new disk space
[root@mastiscsi ~]# echo "- - -" > /sys/class/scsi_host/host0/scan

[root@mastiscsi ~]# fdisk -l /dev/sdc
Disk /dev/sdc: 5368 MB, 5368709120 bytes
255 heads, 63 sectors/track, 652 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/sdc doesn't contain a valid partition table
[root@mastiscsi ~]#

3.             Create LVM to export disk as target
[root@mastiscsi ~]# pvcreate /dev/sdc -t
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
  Writing physical volume data to disk "/dev/sdc"
  Physical volume "/dev/sdc" successfully created

[root@mastiscsi ~]# pvcreate /dev/sdc
  Writing physical volume data to disk "/dev/sdc"
  Physical volume "/dev/sdc" successfully created

[root@mastiscsi ~]# vgcreate multivg /dev/sdc -t
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
  Volume group "multivg" successfully created

[root@mastiscsi ~]# vgcreate multivg /dev/sdc
  Volume group "multivg" successfully created

[root@mastiscsi ~]# lvcreate -L 800MB -n multilv multivg -t
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
  Logical volume "multilv" created

[root@mastiscsi ~]# lvcreate -L 800MB -n multilv multivg
  Logical volume "multilv" created

4.             Check newly created PV, VG ad LVM
[root@mastiscsi ~]# pvdisplay /dev/sdc
  --- Physical volume ---
  PV Name               /dev/sdc
  VG Name               multivg
  PV Size               5.00 GB / not usable 4.00 MB
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              1279
  Free PE               1079
  Allocated PE          200
  PV UUID               Un9URB-fgvf-SBAP-AeAN-7J0I-sLWw-KIWBzI

[root@mastiscsi ~]# vgdisplay multivg
  --- Volume group ---
  VG Name               multivg
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               5.00 GB
  PE Size               4.00 MB
  Total PE              1279
  Alloc PE / Size       200 / 800.00 MB
  Free  PE / Size       1079 / 4.21 GB
  VG UUID               pkBZxW-DM3m-a1dz-9MCM-gKd8-DXpr-i2cEMG

[root@mastiscsi ~]# lvdisplay /dev/multivg/multilv
  --- Logical volume ---
  LV Name                /dev/multivg/multilv
  VG Name                multivg
  LV UUID                vlK9G8-E8lS-bEwX-2w6Z-fAFO-3Rsi-971joA
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                800.00 MB
  Current LE             200
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:4
[root@mastiscsi ~]#

5.             Add disk into /etc/tgt/targets.conf file
[root@mastiscsi ~]# vi /etc/tgt/targets.conf
<target iqn.2015-08.com.example:mastiscsi.disk1>
    backing-store /dev/sdb
</target>

<target iqn.2015-08.com.example:mastiscsi.disk2>
    backing-store /dev/multivg/multilv
</target>

6.             Reload the tgtd service for exporting newly added disk
[root@mastiscsi ~]# /etc/init.d/tgtd reload
Updating target framework daemon configuration


New Disk add on client machine


1.             Discovery disk on master server with both IPs
[root@iscsiclient ~]# iscsiadm -m discoverydb -t st --portal 192.168.144.136:3260 --discover
                192.168.144.136:3260,1 iqn.2015-08.com.example:mastiscsi.disk1
                192.168.144.136:3260,1 iqn.2015-08.com.example:mastiscsi.disk2

[root@iscsiclient ~]# iscsiadm -m discoverydb -t st --portal 192.168.144.155:3260 --discover
                192.168.144.155:3260,1 iqn.2015-08.com.example:mastiscsi.disk1
                192.168.144.155:3260,1 iqn.2015-08.com.example:mastiscsi.disk2

2.             Login into newly added disk on master server with both IPs
[root@iscsiclient ~]# iscsiadm -m node --portal 192.168.144.136:3260 -T iqn.2015-08.com.example:mastiscsi.disk2 -l
Logging in to [iface: default, target: iqn.2015-08.com.example:mastiscsi.disk2, portal: 192.168.144.136,3260] (multiple)
Login to [iface: default, target: iqn.2015-08.com.example:mastiscsi.disk2, portal: 192.168.144.136,3260] successful.

[root@iscsiclient ~]# iscsiadm -m node --portal 192.168.144.155:3260 -T iqn.2015-08.com.example:mastiscsi.disk2 -l
Logging in to [iface: default, target: iqn.2015-08.com.example:mastiscsi.disk2, portal: 192.168.144.155,3260] (multiple)
Login to [iface: default, target: iqn.2015-08.com.example:mastiscsi.disk2, portal: 192.168.144.155,3260] successful.
[root@iscsiclient ~]#

3.             Check newly disk add by multipath command
[root@iscsiclient ~]# multipath -ll
mpath1 (1IET_00020001) dm-7 IET,VIRTUAL-DISK
[size=800M][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 33:0:0:1 sdd 8:48  [active][ready]
\_ round-robin 0 [prio=1][enabled]
 \_ 34:0:0:1 sde 8:64  [active][ready]
mpath0 (1IET_00010001) dm-4 IET,VIRTUAL-DISK
[size=4.0G][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 31:0:0:1 sdb 8:16  [active][ready]
\_ round-robin 0 [prio=1][enabled]
 \_ 32:0:0:1 sdc 8:32  [active][ready]
[root@iscsiclient ~]#

4              Check disk space newly added and visible on multipath output
[root@iscsiclient ~]# fdisk -l

Disk /dev/sda: 42.9 GB, 42949672960 bytes
255 heads, 63 sectors/track, 5221 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          32      257008+  83  Linux
/dev/sda2              33        5221    41680642+  8e  Linux LVM

Disk /dev/sdb: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1         522     4192933+  8e  Linux LVM

Disk /dev/sdc: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1         522     4192933+  8e  Linux LVM

Disk /dev/dm-4: 4294 MB, 4294967296 bytes
255 heads, 63 sectors/track, 522 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

     Device Boot      Start         End      Blocks   Id  System
/dev/dm-4p1               1         522     4192933+  8e  Linux LVM

Disk /dev/dm-5: 4293 MB, 4293563904 bytes
255 heads, 63 sectors/track, 521 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/dm-5 doesn't contain a valid partition table

Disk /dev/sdd: 838 MB, 838860800 bytes
26 heads, 62 sectors/track, 1016 cylinders
Units = cylinders of 1612 * 512 = 825344 bytes

Disk /dev/sdd doesn't contain a valid partition table

Disk /dev/dm-7: 838 MB, 838860800 bytes
255 heads, 63 sectors/track, 101 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/dm-7 doesn't contain a valid partition table

Disk /dev/sde: 838 MB, 838860800 bytes
26 heads, 62 sectors/track, 1016 cylinders
Units = cylinders of 1612 * 512 = 825344 bytes

Disk /dev/sde doesn't contain a valid partition table
[root@iscsiclient ~]#

5.             List current device mapper
[root@iscsiclient ~]# ls -l /dev/mapper/
total 0
crw------- 1 root root  10, 60 Aug 27 19:03 control
brw-rw---- 1 root disk 253,  4 Aug 27 19:04 mpath0
brw-rw---- 1 root disk 253,  5 Aug 27 19:39 mpath0p1
brw-rw---- 1 root disk 253,  7 Aug 27 21:30 mpath1
brw-rw---- 1 root disk 253,  2 Aug 27 19:03 vg0-home
brw-rw---- 1 root disk 253,  0 Aug 27 19:03 vg0-root
brw-rw---- 1 root disk 253,  3 Aug 27 19:03 vg0-swap
brw-rw---- 1 root disk 253,  1 Aug 27 19:03 vg0-var
brw-rw---- 1 root disk 253,  6 Aug 27 19:44 wasvg-wasvg--datalv

6.             Now partition the newly added disk
[root@iscsiclient ~]# fdisk -l /dev/mapper/mpath1
Disk /dev/mapper/mpath1: 838 MB, 838860800 bytes
255 heads, 63 sectors/track, 101 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Disk /dev/mapper/mpath1 doesn't contain a valid partition table

[root@iscsiclient ~]# fdisk /dev/mapper/mpath1
Command (m for help): p

Disk /dev/mapper/mpath1: 838 MB, 838860800 bytes
255 heads, 63 sectors/track, 101 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p

Partition number (1-4): 1
First cylinder (1-101, default 1): <enter>
Using default value 1
Last cylinder or +size or +sizeM or +sizeK (1-101, default 101): <enter>
Using default value 101

Command (m for help): p

Disk /dev/mapper/mpath1: 838 MB, 838860800 bytes
255 heads, 63 sectors/track, 101 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath1p1               1         101      811251   83  Linux

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 8e
Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): p

Disk /dev/mapper/mpath1: 838 MB, 838860800 bytes
255 heads, 63 sectors/track, 101 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath1p1               1         101      811251   8e  Linux LVM

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

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.

[root@iscsiclient ~]# fdisk -l /dev/mapper/mpath1
Disk /dev/mapper/mpath1: 838 MB, 838860800 bytes
255 heads, 63 sectors/track, 101 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath1p1               1         101      811251   8e  Linux LVM

[root@iscsiclient ~]# partprobe /dev/mapper/mpath1
[root@iscsiclient ~]# partprobe /dev/mapper/mpath1p1

7.             Create PV, VG and LVM on new partition
[root@iscsiclient ~]# pvcreate /dev/mapper/mpath1p1 -t
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
  Writing physical volume data to disk "/dev/mapper/mpath1p1"
  Physical volume "/dev/mapper/mpath1p1" successfully created

[root@iscsiclient ~]# pvcreate /dev/mapper/mpath1p1
  Writing physical volume data to disk "/dev/mapper/mpath1p1"
  Physical volume "/dev/mapper/mpath1p1" successfully created

[root@iscsiclient ~]# vgcreate mpath1vg /dev/mapper/mpath1p1 -t
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
  Volume group "mpath1vg" successfully created

[root@iscsiclient ~]# vgcreate mpath1vg /dev/mapper/mpath1p1
  Volume group "mpath1vg" successfully created

[root@iscsiclient ~]# lvcreate -L 600M  -n mpath1-lv mpath1vg -t
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
  Logical volume "mpath1-lv" created

[root@iscsiclient ~]# lvcreate -L 600M  -n mpath1-lv mpath1vg
  Logical volume "mpath1-lv" created

8.             Display PV, VG and LVM
[root@iscsiclient ~]# pvdisplay /dev/mapper/mpath1p1
  --- Physical volume ---
  PV Name               /dev/mapper/mpath1p1
  VG Name               mpath1vg
  PV Size               792.24 MB / not usable 243.00 KB
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              198
  Free PE               48
  Allocated PE          150
  PV UUID               PvY0Jc-LWfy-Cz9F-93v4-8a8T-GRCc-72wkHd

[root@iscsiclient ~]# vgdisplay mpath1vg
  --- Volume group ---
  VG Name               mpath1vg
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               792.00 MB
  PE Size               4.00 MB
  Total PE              198
  Alloc PE / Size       150 / 600.00 MB
  Free  PE / Size       48 / 192.00 MB
  VG UUID               33jdf6-tP2I-pXm6-kioh-OWvm-fL69-mnswiQ

[root@iscsiclient ~]# lvdisplay /dev/mpath1vg/mpath1-lv
  --- Logical volume ---
  LV Name                /dev/mpath1vg/mpath1-lv
  VG Name                mpath1vg
  LV UUID                L1ZDxM-WTwI-792x-qU1e-hFmi-8SP1-jGoqXe
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                600.00 MB
  Current LE             150
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:9

[root@iscsiclient ~]#

9.             Create File System on newly added disk
[root@iscsiclient /]# mkfs -t ext3 /dev/mpath1vg/mpath1-lv
mke2fs 1.39 (29-May-2006)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
76800 inodes, 153600 blocks
7680 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=159383552
5 block groups
32768 blocks per group, 32768 fragments per group
15360 inodes per group
Superblock backups stored on blocks:
        32768, 98304

Writing inode tables: done
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 34 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

10.          Mount file system and check
[root@iscsiclient /]# mount -t ext3 /dev/mpath1vg/mpath1-lv /mpath1-lv/

[root@iscsiclient /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg0-root   20G  3.1G   16G  17% /
/dev/mapper/vg0-var   9.7G  222M  9.0G   3% /var
/dev/mapper/vg0-home  992M   34M  908M   4% /home
/dev/sda1             244M   14M  218M   6% /boot
tmpfs                 500M     0  500M   0% /dev/shm
/dev/mapper/mpath0p1  4.0G   73M  3.7G   2% /datalv
/dev/mapper/mpath1vg-mpath1--lv
                      591M   17M  545M   3% /mpath1-lv
[root@iscsiclient /]#

11.          Creating file in newly created file system
[root@iscsiclient /]# ls -l > /mpath1-lv/ls-l.txt
[root@iscsiclient /]# ls -l /mpath1-lv/
total 20
drwx------ 2 root root 16384 Aug 29 15:22 lost+found
-rw-r--r-- 1 root root  1245 Aug 29 15:23 ls-l.txt
[root@iscsiclient /]#


Extend (resize) disk on master


1.             View Current disk space on Master Server

 [root@mastiscsi ~]# pvdisplay /dev/sdc
  --- Physical volume ---
  PV Name               /dev/sdc
  VG Name               multivg
  PV Size               5.00 GB / not usable 4.00 MB
  Allocatable           yes
  PE Size (KByte)       4096
  Total PE              1279
  Free PE               1079
  Allocated PE          200
  PV UUID               Un9URB-fgvf-SBAP-AeAN-7J0I-sLWw-KIWBzI

[root@mastiscsi ~]# vgdisplay multivg
  --- Volume group ---
  VG Name               multivg
  System ID
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               0
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               5.00 GB
  PE Size               4.00 MB
  Total PE              1279
  Alloc PE / Size       200 / 800.00 MB
  Free  PE / Size       1079 / 4.21 GB
  VG UUID               pkBZxW-DM3m-a1dz-9MCM-gKd8-DXpr-i2cEMG

[root@mastiscsi ~]# lvdisplay /dev/multivg/multilv
  --- Logical volume ---
  LV Name                /dev/multivg/multilv
  VG Name                multivg
  LV UUID                vlK9G8-E8lS-bEwX-2w6Z-fAFO-3Rsi-971joA
  LV Write Access        read/write
  LV Status              available
  # open                 0
  LV Size                800.00 MB
  Current LE             200
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:4
[root@mastiscsi ~]#

2.             Extend LVM on Master server
--------------------------
[root@mastiscsi ~]# lvextend -L +100MB /dev/multivg/multilv -t
 
[root@mastiscsi ~]# lvextend -L +100MB /dev/multivg/multilv
  Extending logical volume multilv to 900.00 MB
  Logical volume multilv successfully resized

[root@mastiscsi ~]# lvdisplay /dev/multivg/multilv
  --- Logical volume ---
  LV Name                /dev/multivg/multilv
  VG Name                multivg
  LV UUID                vlK9G8-E8lS-bEwX-2w6Z-fAFO-3Rsi-971joA
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                900.00 MB
  Current LE             225
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:4

[root@mastiscsi ~]#

2.             Show target details
[root@mastiscsi ~]# tgtadm --op show --mode target

Target 1: iqn.2015-08.com.example:mastiscsi.disk1
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
        I_T nexus: 7
            Initiator: iqn.2015-08.com.example:mastiscsi
            Connection: 0
                IP Address: 192.168.144.153
        I_T nexus: 10
            Initiator: iqn.2015-08.com.example:mastiscsi
            Connection: 0
                IP Address: 192.168.144.153
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00010000
            SCSI SN: beaf10
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: 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
            Readonly: No
            Backing store type: rdwr
            Backing store path: /dev/sdb
            Backing store flags:
    Account information:
    ACL information:
        ALL
Target 2: iqn.2015-08.com.example:mastiscsi.disk2
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
        I_T nexus: 8
            Initiator: iqn.2015-08.com.example:mastiscsi
            Connection: 0
                IP Address: 192.168.144.153
        I_T nexus: 9
            Initiator: iqn.2015-08.com.example:mastiscsi
            Connection: 0
                IP Address: 192.168.144.153
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00020000
            SCSI SN: beaf20
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Readonly: No
            Backing store type: null
            Backing store path: None
            Backing store flags:
        LUN: 1
            Type: disk
            SCSI ID: IET     00020001
            SCSI SN: beaf21
            Size: 839 MB, Block size: 512
            Online: Yes
            Removable media: No
            Readonly: No
            Backing store type: rdwr
            Backing store path: /dev/multivg/multilv
            Backing store flags:
    Account information:
    ACL information:
        ALL

3.             Delete logical unit 1 and target 2 temporarily, it will not effect on client side
[root@mastiscsi ~]# tgtadm --op delete --mode logicalunit --tid=2 --lun=1

4.             View exported target backup-store path
[root@mastiscsi ~]# more /etc/tgt/targets.conf
<target iqn.2015-08.com.example:mastiscsi.disk1>
    backing-store /dev/sdb
</target>

<target iqn.2015-08.com.example:mastiscsi.disk2>
    backing-store /dev/multivg/multilv
</target>

5.             Again add new logical unit 1 and target 2
[root@mastiscsi ~]# tgtadm --op new --mode logicalunit --tid=2 --lun=1 --backing-store /dev/multivg/multilv

6.             Check newly updated size
[root@mastiscsi ~]# tgtadm --op show --mode target
                :
                :
                :
Target 2: iqn.2015-08.com.example:mastiscsi.disk2
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
        I_T nexus: 8
            Initiator: iqn.2015-08.com.example:mastiscsi
            Connection: 0
                IP Address: 192.168.144.153
        I_T nexus: 9
            Initiator: iqn.2015-08.com.example:mastiscsi
            Connection: 0
                IP Address: 192.168.144.153
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00020000
            SCSI SN: beaf20
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Readonly: No
            Backing store type: null
            Backing store path: None
            Backing store flags:
        LUN: 1
            Type: disk
            SCSI ID: IET     00020001
            SCSI SN: beaf21
            Size: 944 MB, Block size: 512
            Online: Yes
            Removable media: No
            Readonly: No
            Backing store type: rdwr
            Backing store path: /dev/multivg/multilv
            Backing store flags:
    Account information
    ACL information:
        ALL
[root@mastiscsi ~]#


Same output can also be check by below command

[root@mastiscsi ~]# tgt-admin -s
                :
                :
                :
Target 2: iqn.2015-08.com.example:mastiscsi.disk2
    System information:
        Driver: iscsi
        State: ready
    I_T nexus information:
        I_T nexus: 8
            Initiator: iqn.2015-08.com.example:mastiscsi
            Connection: 0
                IP Address: 192.168.144.153
        I_T nexus: 9
            Initiator: iqn.2015-08.com.example:mastiscsi
            Connection: 0
                IP Address: 192.168.144.153
    LUN information:
        LUN: 0
            Type: controller
            SCSI ID: IET     00020000
            SCSI SN: beaf20
            Size: 0 MB, Block size: 1
            Online: Yes
            Removable media: No
            Readonly: No
            Backing store type: null
            Backing store path: None
            Backing store flags:
        LUN: 1
            Type: disk
            SCSI ID: IET     00020001
            SCSI SN: beaf21
            Size: 944 MB, Block size: 512
            Online: Yes
            Removable media: No
            Readonly: No
            Backing store type: rdwr
            Backing store path: /dev/multivg/multilv
            Backing store flags:
    Account information:
    ACL information:
        ALL
[root@mastiscsi ~]#



Scan newly updated size on client machine


1.             Check current disk size
[root@iscsiclient ~]# multipath -ll
mpath1 (1IET_00020001) dm-5 IET,VIRTUAL-DISK
[size=800M][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 34:0:0:1 sdc 8:32  [active][ready]
\_ round-robin 0 [prio=1][enabled]
 \_ 33:0:0:1 sdd 8:48  [active][ready]
mpath0 (1IET_00010001) dm-4 IET,VIRTUAL-DISK
[size=4.0G][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 31:0:0:1 sdb 8:16  [active][ready]
\_ round-robin 0 [prio=1][enabled]
 \_ 32:0:0:1 sde 8:64  [active][ready]

2.             Scan block device
[root@iscsiclient ~]# echo 1 > /sys/block/sdc/device/rescan
[root@iscsiclient ~]# echo 1 > /sys/block/sdd/device/rescan

3.             Check disk but not update
[root@iscsiclient ~]# multipath -ll
mpath1 (1IET_00020001) dm-5 IET,VIRTUAL-DISK
[size=800M][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 34:0:0:1 sdc 8:32  [active][ready]
\_ round-robin 0 [prio=1][enabled]
 \_ 33:0:0:1 sdd 8:48  [active][ready]
mpath0 (1IET_00010001) dm-4 IET,VIRTUAL-DISK
[size=4.0G][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 31:0:0:1 sdb 8:16  [active][ready]
\_ round-robin 0 [prio=1][enabled]
 \_ 32:0:0:1 sde 8:64  [active][ready]

4.             Resize map by multipathd command
[root@iscsiclient ~]# multipathd -k'resize map mpath1'
ok

Note: above space between –k and 'resize map mpath1' NOT allow

5.             Check disk, now size updated
[root@iscsiclient ~]# multipath –ll
mpath1 (1IET_00020001) dm-5 IET,VIRTUAL-DISK
[size=900M][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 34:0:0:1 sdc 8:32  [active][ready]
\_ round-robin 0 [prio=1][enabled]
 \_ 33:0:0:1 sdd 8:48  [active][ready]
mpath0 (1IET_00010001) dm-4 IET,VIRTUAL-DISK
[size=4.0G][features=0][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 31:0:0:1 sdb 8:16  [active][ready]
\_ round-robin 0 [prio=1][enabled]
 \_ 32:0:0:1 sde 8:64  [active][ready]
[root@iscsiclient ~]#

6.             Check disk space
[root@iscsiclient /]# fdisk -l /dev/mapper/mpath1

Disk /dev/mapper/mpath1: 943 MB, 943718400 bytes
255 heads, 63 sectors/track, 114 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath1p1               1         101      811251   8e  Linux LVM

7.             Make disk partition for extending LVM

[root@iscsiclient /]# fdisk /dev/mapper/mpath1

Command (m for help): p

Disk /dev/mapper/mpath1: 943 MB, 943718400 bytes
255 heads, 63 sectors/track, 114 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath1p1               1         101      811251   8e  Linux LVM

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (102-114, default 102): <enter>
Using default value 102
Last cylinder or +size or +sizeM or +sizeK (102-114, default 114): <enter>
Using default value 114

Command (m for help): p

Disk /dev/mapper/mpath1: 943 MB, 943718400 bytes
255 heads, 63 sectors/track, 114 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath1p1               1         101      811251   8e  Linux LVM
/dev/mapper/mpath1p2             102         114      104422+  83  Linux

Command (m for help): t
Partition number (1-4): 2
Hex code (type L to list codes): 8e
Changed system type of partition 2 to 8e (Linux LVM)

Command (m for help): p

Disk /dev/mapper/mpath1: 943 MB, 943718400 bytes
255 heads, 63 sectors/track, 114 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

              Device Boot      Start         End      Blocks   Id  System
/dev/mapper/mpath1p1               1         101      811251   8e  Linux LVM
/dev/mapper/mpath1p2             102         114      104422+  8e  Linux LVM

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

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 22: Invalid argument.
The kernel still uses the old table.
The new table will be used at the next reboot.
Syncing disks.

[root@iscsiclient /]# partprobe /dev/mapper/mpath1
device-mapper: remove ioctl failed: Device or resource busy
Warning: parted was unable to re-read the partition table on /dev/mapper/mpath1 (Device or resource busy).  This means Linux won't know anything about the modifications you made.
device-mapper: create ioctl failed: Device or resource busy
device-mapper: remove ioctl failed: Device or resource busy

[root@iscsiclient /]# partprobe /dev/mapper/mpath1p2

Note: above both commands (partprobe /dev/mapper/mpath1 & partprobe /dev/mapper/mpath1p2) require to run. Error comes on first command. It is ok

8.             Check new device mapper list
[root@iscsiclient /]# ls -l /dev/mapper/
total 0
crw------- 1 root root  10, 60 Aug 28 18:37 control
brw-rw---- 1 root disk 253,  4 Aug 28 18:37 mpath0
brw-rw---- 1 root disk 253,  7 Aug 29 14:58 mpath0p1
brw-rw---- 1 root disk 253,  5 Aug 29 15:35 mpath1
brw-rw---- 1 root disk 253,  6 Aug 29 14:54 mpath1p1
brw-rw---- 1 root disk 253,  9 Aug 29 15:36 mpath1p2
brw-rw---- 1 root disk 253,  8 Aug 29 15:22 mpath1vg-mpath1--lv
brw-rw---- 1 root disk 253,  2 Aug 28 18:37 vg0-home
brw-rw---- 1 root disk 253,  0 Aug 28 18:37 vg0-root
brw-rw---- 1 root disk 253,  3 Aug 28 18:37 vg0-swap
brw-rw---- 1 root disk 253,  1 Aug 28 18:37 vg0-var
[root@iscsiclient /]#

9.             Create PV and extend VG & LVM
[root@iscsiclient /]# pvcreate /dev/mapper/mpath1p2 -t
[root@iscsiclient /]# pvcreate /dev/mapper/mpath1p2

[root@iscsiclient /]# vgextend mpath1vg /dev/mapper/mpath1p2 -t
[root@iscsiclient /]# vgextend mpath1vg /dev/mapper/mpath1p2

[root@iscsiclient /]# lvextend -l +100%FREE /dev/mpath1vg/mpath1-lv -t
  Test mode: Metadata will NOT be updated and volumes will not be (de)activated.
  Extending logical volume mpath1-lv to 892.00 MB
  Logical volume mpath1-lv successfully resized

[root@iscsiclient /]# lvextend -l +100%FREE /dev/mpath1vg/mpath1-lv
  Extending logical volume mpath1-lv to 892.00 MB
  Logical volume mpath1-lv successfully resized

Note: for specific size run below command
[root@iscsiclient /]# lvextend -L +500M /dev/mpath1vg/mpath1-lv

10.          Resize file system
[root@iscsiclient /]# resize2fs /dev/mpath1vg/mpath1-lv
resize2fs 1.39 (29-May-2006)
Filesystem at /dev/mpath1vg/mpath1-lv is mounted on /mpath1-lv; on-line resizing required
Performing an on-line resize of /dev/mpath1vg/mpath1-lv to 228352 (4k) blocks.
The filesystem on /dev/mpath1vg/mpath1-lv is now 228352 blocks long.

11.          Check disk space
[root@iscsiclient /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg0-root   20G  3.1G   16G  17% /
/dev/mapper/vg0-var   9.7G  222M  9.0G   3% /var
/dev/mapper/vg0-home  992M   34M  908M   4% /home
/dev/sda1             244M   14M  218M   6% /boot
tmpfs                 500M     0  500M   0% /dev/shm
/dev/mapper/mpath0p1  4.0G   73M  3.7G   2% /datalv
/dev/mapper/mpath1vg-mpath1--lv
                      879M   17M  820M   2% /mpath1-lv
[root@iscsiclient /]#