Steps to Move ISCSI Target to Another Linux Server

In a recent blog, we saw Steps to Connect And Mount ISCSI Target on Linux Server Click here to read more. In this blog, we will see How we can shift the same iSCSI target to another Server. We are expected to do this kind of task when there is an application or DB migration to a new server and iSCSI targets were used to store of backups or application files outside of the server in iSCSI drives.

In the below demo we will shift /scan mount point from Server test-machine01 is partition created on iSCSI Lun to new Server: test-machine02.

Follow below Steps
1. Install iscsi-initiator-utils rpm package in Target Server
2. Stop dependent services on iSCSI and umount /scan in Source Server
3. Logout and Remove iSCSI target in Source Server
4. Discovering & Login to iSCSI targets LUN in Target Server
5. Mount the partition in Target Server
6. Start dependent Services in Target Server

Step 1. Install iscsi-initiator-utils rpm package in Target Server: To use the Linux system as an iSCSI initiator or client, We need to install iscsi-initiator-utils rpm package. Use OS yum command to install the required packages. Please note we are using OLE 7.9 for this demo. Once installation is done share initiator name with Storage admin. Initiator name is required to map iSCSI Lun to the new Server.

[root@test-machine02 ~]#
[root@test-machine02 ~]# cat /etc/oracle-release
Oracle Linux Server release 7.9
[root@test-machine02 ~]#
 
[root@test-machine02 ~]# yum install iscsi-initiator-utils
Resolving Dependencies
--> Running transaction check
--> Finished Dependency Resolution
 
Dependencies Resolved
 
==============================================================================================================================================================================================
 Package                                                   Arch                              Version                                              Repository                             Size
==============================================================================================================================================================================================
Installing:
 iscsi-initiator-utils                                     x86_64                            6.2.0.874-22.0.1.el7_9                               ol7_latest                            429 k
Installing for dependencies:
 iscsi-initiator-utils-iscsiuio                            x86_64                            6.2.0.874-22.0.1.el7_9                               ol7_latest                             96 k
 
Transaction Summary
==============================================================================================================================================================================================
Install  1 Package (+1 Dependent package)
 
Total download size: 524 k
Installed size: 2.5 M
Is this ok [y/d/N]: y
Downloading packages:
(1/2): iscsi-initiator-utils-iscsiuio-6.2.0.874-22.0.1.el7_9.x86_64.rpm                                                                                                |  96 kB  00:00:01
(2/2): iscsi-initiator-utils-6.2.0.874-22.0.1.el7_9.x86_64.rpm                                                                                                         | 429 kB  00:00:02
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Total                                                                                                                                                         224 kB/s | 524 kB  00:00:02
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : iscsi-initiator-utils-iscsiuio-6.2.0.874-22.0.1.el7_9.x86_64                                                                                                               1/2
  Installing : iscsi-initiator-utils-6.2.0.874-22.0.1.el7_9.x86_64                                                                                                                        2/2
  Verifying  : iscsi-initiator-utils-6.2.0.874-22.0.1.el7_9.x86_64                                                                                                                        1/2
  Verifying  : iscsi-initiator-utils-iscsiuio-6.2.0.874-22.0.1.el7_9.x86_64                                                                                                               2/2
 
Installed:
  iscsi-initiator-utils.x86_64 0:6.2.0.874-22.0.1.el7_9
 
Dependency Installed:
  iscsi-initiator-utils-iscsiuio.x86_64 0:6.2.0.874-22.0.1.el7_9
 
Complete!
[root@test-machine02 ~]#
 
[root@test-machine02 ~]#
[root@test-machine02 ~]# rpm -qa |grep iscsi
iscsi-initiator-utils-iscsiuio-6.2.0.874-22.0.1.el7_9.x86_64
iscsi-initiator-utils-6.2.0.874-22.0.1.el7_9.x86_64
[root@test-machine02 ~]#

[root@test-machine02 iscsi]#
[root@test-machine02 iscsi]# cat /etc/iscsi/initiatorname.iscsi
InitiatorName=iqn.1988-12.com.oracle:f43ac3fda4a3
[root@test-machine02 iscsi]#

Step 2. Stop dependent services on iSCSI and umount /scan in Source Server: Stop the dependent services on /scan mount point. We were using /scan as nfs and samba share for application. Once service is stopped disable service and comment out in /etc/fstab so the server will not attempt to mount /scan. Make sure /scan mount point is not in use and umount the /scan. Please note we already have 39Gb of data in /scan mount point and two application folder Image and attach.

[root@test-machine01 ~]# 
[root@test-machine01 ~]# service nfs stop
Shutting down NFS daemon:                                  [  OK  ]
Shutting down NFS mountd:                                  [  OK  ]
Shutting down NFS quotas:                                  [  OK  ]
[root@test-machine01 ~]#
[root@test-machine01 ~]# service smb stop
Shutting down SMB services:                                [  OK  ]
[root@test-machine01 ~]#

[root@test-machine01 ~]#
[root@test-machine01 ~]# chkconfig nfs off
[root@test-machine01 ~]#
[root@test-machine01 ~]# chkconfig smb off
[root@test-machine01 ~]#

[root@test-machine01 ~]#
[root@test-machine01 ~]#  df -Th /scan
Filesystem     Type  Size  Used Avail Use% Mounted on
/dev/sda1      ext4 1008G   39G  918G   5% /scan
[root@test-machine01 ~]#
[root@test-machine01 ~]#

[root@test-machine01 ~]#
[root@test-machine01 ~]# ls -ltr /scan
total 2260
drwx------. 2 root       root         16384 Oct 22  2020 lost+found
drwxrwxrwx. 2 app_user app_user    4096 Dec  9 12:30 Image
drwxrwxrwx. 3 app_user app_user 2293760 Jan 18 12:20 attach
[root@test-machine01 ~]#
[root@test-machine01 ~]#

[root@test-machine01 ~]# vi /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sun Sep 29 12:18:09 2019
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/vg_jedoda2-lv_root /                       ext4    defaults        1 1
UUID=3e2509f5-45e1-4591-8e72-93ca17cef43e /boot                   ext4    defaults        1 2
/dev/mapper/vg_jedoda2-lv_swap swap                    swap    defaults        0 0
tmpfs                   /dev/shm                tmpfs   defaults        0 0
devpts                  /dev/pts                devpts  gid=5,mode=620  0 0
sysfs                   /sys                    sysfs   defaults        0 0
proc                    /proc                   proc    defaults        0 0
UUID=59d33c45-551b-4d56-9565-5eedefd56b2d       /app            ext4    defaults                  0 0
#UUID="eab28b6a-910f-4ba2-8e4e-6db9c6af2012"    /scan   ext4  _netdev  0 0
:wq!
[root@test-machine01 ~]#

[root@test-machine01 ~]#
[root@test-machine01 ~]# umount /scan
[root@test-machine01 ~]#

[root@test-machine01 ~]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/vg_test-machine01-lv_root
                       26G  4.5G   21G  19% /
tmpfs                  15G  296K   15G   1% /dev/shm
/dev/vda1             477M   78M  370M  18% /boot
/dev/mapper/vg_test-machine01-lv_app
                       40G  7.1G   31G  19% /app
[root@test-machine01 ~]#

Step 3. Logout and Remove iSCSI target in Source Server: Log out from iSCSI targets as we will not be using this iSCSI lun anymore on this server. You can also delete the target record from this server for the safer side. Once the iSCSI target is logout and target record are deleted, confirm to Storage Admin so he can present iSCSI luns to a new server.

[root@test-machine01 ~]#
[root@test-machine01 ~]#
[root@test-machine01 ~]#  /sbin/iscsiadm -m session -P 0
tcp: [1] 192.168.100.133:3260,1 iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target (non-flash)
[root@test-machine01 ~]#
[root@test-machine01 ~]# iscsiadm --mode node --target iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target --portal 192.168.100.133 --logout
Logging out of session [sid: 1, target: iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target, portal: 192.168.100.133,3260]
Logout of [sid: 1, target: iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target, portal: 192.168.100.133,3260] successful.
[root@test-machine01 ~]#
[root@test-machine01 ~]#
[root@test-machine01 ~]#  /sbin/iscsiadm -m session -P 0
iscsiadm: No active sessions.
[root@test-machine01 ~]#
[root@test-machine01 ~]#  iscsiadm -m session -R
iscsiadm: No session found.
[root@test-machine01 ~]#
[root@test-machine01 ~]# iscsiadm -m node --targetname iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target -p 192.168.100.133  -o update -n node.startup -v manual
[root@test-machine01 ~]#
[root@test-machine01 ~]# iscsiadm -m node --targetname iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target -p 192.168.100.133  -o delete
[root@test-machine01 ~]#

Step 4. Discovering & Login to iSCSI targets LUN in Target Server: Once storage admin confirms iSCSI luns are presented to a new server. We can login to targets and enable automatic login so no manual steps are required, once the server is rebooted. Verify-in /var/log/messages file will get device name for lun. As the luns are already partitioned and formatted with ext4 file system we can directly mount the device to our new Server. Use command blkid to get the UUID of the device and make an entry in /etc/fstab.

[root@test-machine02 ~]#
[root@test-machine02 ~]#
[root@test-machine02 ~]# /sbin/iscsiadm -m discovery -t sendtargets -p 192.168.100.133
192.168.100.133:3260,1 iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target
[root@test-machine02 ~]#
[root@test-machine02 ~]# /sbin/iscsiadm -m node -T iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target  -p 192.168.100.133 -l
Logging in to [iface: default, target: iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target, portal: 192.168.100.133,3260] (multiple)
Login to [iface: default, target: iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target, portal: 192.168.100.133,3260] successful.
[root@test-machine02 ~]#
[root@test-machine02 ~]# /sbin/iscsiadm -m node -T iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target  -p 192.168.100.133 --op update -n node.startup -v automatic
[root@test-machine02 ~]#
[root@test-machine02 ~]#  /sbin/iscsiadm -m session -P 0
tcp: [1] 192.168.100.133:3260,1 iqn.1991-05.com.microsoft:storsimple8600-shg0997877l71en-target (non-flash)
[root@test-machine02 ~]#
[root@test-machine02 ~]#
[root@test-machine02 ~]# cd /var/log
[root@test-machine02 log]#
[root@test-machine02 log]# ls -l mess*
-rw-------. 1 root root  349156 Jan 18 12:10 messages
-rw-------. 1 root root  893907 Jan  2 03:12 messages-20220102
-rw-------. 1 root root 1060113 Jan  9 03:10 messages-20220109
-rw-------. 1 root root 1063258 Jan 16 03:10 messages-20220116
[root@test-machine02 log]#
[root@test-machine02 log]# vi messages
Jan 18 12:10:59 test-machine02 kernel: scsi 3:0:0:3: Direct-Access     MSFT     STORSIMPLE 8600  221  PQ: 0 ANSI: 6
Jan 18 12:10:59 test-machine02 kernel: sd 3:0:0:3: Attached scsi generic sg3 type 0
Jan 18 12:10:59 test-machine02 kernel: sd 3:0:0:3: [sdc] 2147483648 512-byte logical blocks: (1.10 TB/1.00 TiB)
Jan 18 12:10:59 test-machine02 kernel: sd 3:0:0:3: [sdc] Write Protect is off
Jan 18 12:10:59 test-machine02 kernel: sd 3:0:0:3: [sdc] Write cache: disabled, read cache: enabled, supports DPO and FUA
Jan 18 12:10:59 test-machine02 kernel: sdc: sdc1
Jan 18 12:10:59 test-machine02 kernel: sd 3:0:0:3: [sdc] Attached SCSI disk
[root@test-machine02 log]#
[root@test-machine02 log]# fdisk -l

Disk /dev/sda: 53.7 GB, 53687091200 bytes, 104857600 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 1048576 bytes
Disk label type: dos
Disk identifier: 0x000a8920

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     2099199     1048576   83  Linux
/dev/sda2         2099200   104857599    51379200   8e  Linux LVM

Disk /dev/sdb: 161.1 GB, 161061273600 bytes, 314572800 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 1048576 bytes
Disk label type: dos
Disk identifier: 0x8e917b78

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048   314572799   157285376   83  Linux

Disk /dev/mapper/ol_test-machine02-root: 47.2 GB, 47240445952 bytes, 92266496 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 1048576 bytes


Disk /dev/mapper/ol_test-machine02-swap: 5368 MB, 5368709120 bytes, 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 1048576 bytes


Disk /dev/sdc: 1099.5 GB, 1099511627776 bytes, 2147483648 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: 0x1b167028

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1              63  2147472809  1073736373+  83  Linux
[root@test-machine02 log]#
[root@test-machine02 log]# blkid
/dev/sda1: UUID="9bd3f9f7-734c-4ef5-8bc2-c86df5a79c98" TYPE="xfs"
/dev/sda2: UUID="bSyqN1-dOx9-Sgob-LzlG-iyot-Ci3L-y3HU5j" TYPE="LVM2_member"
/dev/sdb1: UUID="32ab5545-f26f-4fd1-8dee-2cd873a0ea0f" TYPE="xfs"
/dev/mapper/ol_test-machine02-root: UUID="7f0c04c4-21c4-4b02-a495-3f6f9c96a9ca" TYPE="xfs"
/dev/mapper/ol_test-machine02-swap: UUID="89709dec-a9ab-449d-8d24-575961fff8e4" TYPE="swap"
/dev/sdc1: UUID="eab28b6a-910f-4ba2-8e4e-6db9c6af2012" TYPE="ext4"
[root@test-machine02 log]#
[root@test-machine02 log]# lsblk
NAME                    MAJ:MIN RM  SIZE RO TYPE MOUNTPOINT
sdb                       8:16   0  150G  0 disk
ââsdb1                    8:17   0  150G  0 part /app
sr0                      11:0    1 1024M  0 rom
sdc                       8:32   0    1T  0 disk
ââsdc1                    8:33   0 1024G  0 part
sda                       8:0    0   50G  0 disk
ââsda2                    8:2    0   49G  0 part
â ââol_test-machine02-swap 252:1    0    5G  0 lvm  [SWAP]
â ââol_test-machine02-root 252:0    0   44G  0 lvm  /
ââsda1                    8:1    0    1G  0 part /boot
[root@test-machine02 log]#
[root@test-machine02 log]# vi /etc/fstab
#
# /etc/fstab
# Created by anaconda on Wed Dec 29 12:37:55 2021
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/ol_test-machine02-root /                       xfs     defaults        0 0
UUID=9bd3f9f7-734c-4ef5-8bc2-c86df5a79c98 /boot                   xfs     defaults        0 0
/dev/mapper/ol_test-machine02-swap swap                    swap    defaults        0 0
UUID=32ab5545-f26f-4fd1-8dee-2cd873a0ea0f      /app       xfs    defaults               0 0
UUID="eab28b6a-910f-4ba2-8e4e-6db9c6af2012"    /scan   ext4  _netdev  0 0
:wq!
[root@test-machine02 log]#

Step 5. Mount the partition in Target Server: Create one folder scan in the root directory / and use command mount -a to mount /scan mount point. Also, correct the owner and permission on /scan and directories.

[root@test-machine02 log]#
[root@test-machine02 log]# cd /
[root@test-machine02 /]#
[root@test-machine02 /]# mkdir scan
[root@test-machine02 /]#
[root@test-machine02 /]# mount -a
[root@test-machine02 /]#
[root@test-machine02 /]# df -h
Filesystem                       Size  Used Avail Use% Mounted on
devtmpfs                          12G     0   12G   0% /dev
tmpfs                             12G     0   12G   0% /dev/shm
tmpfs                             12G   34M   12G   1% /run
tmpfs                             12G     0   12G   0% /sys/fs/cgroup
/dev/mapper/ol_test-machine02-root   44G  6.5G   38G  15% /
/dev/sdb1                        150G  126M  150G   1% /app
/dev/sda1                       1014M  306M  709M  31% /boot
tmpfs                            2.4G   36K  2.4G   1% /run/user/1000
tmpfs                            2.4G   12K  2.4G   1% /run/user/42
tmpfs                            2.4G     0  2.4G   0% /run/user/0
/dev/sdc1                       1008G   39G  918G   5% /scan
[root@test-machine02 /]#
[root@test-machine02 /]# cd /scan
[root@test-machine02 scan]# ls
attach  lost+found  SignImage
[root@test-machine02 scan]# ls -ltr
total 2260
drwx------. 2 root root   16384 Oct 22  2020 lost+found
drwxrwxrwx. 2  500  500    4096 Dec  9 12:30 Image
drwxrwxrwx. 3  500  500 2293760 Jan 18 10:21 attach
[root@test-machine02 scan]#
[root@test-machine02 scan]#
[root@test-machine02 ~]#
[root@test-machine02 ~]#
[root@test-machine02 ~]# chown app_user:app_user /scan
[root@test-machine02 ~]#
[root@test-machine02 ~]# ls -ld /scan
drwxrwxr-x. 6 app_user app_user 4096 Jan 18 05:38 /scan
[root@test-machine02 ~]#
[root@test-machine02 ~]#
[root@test-machine02 ~]# cd /scan
[root@test-machine02 scan]# ls -ltr
total 2260
drwx------. 2 root root   16384 Oct 22  2020 lost+found
drwxrwxrwx. 2  500  500    4096 Dec  9 12:30 Image
drwxrwxrwx. 3  500  500 2293760 Jan 18 10:21 attach
[root@test-machine02 scan]#
[root@test-machine02 scan]# chown app_user:app_user Image
[root@test-machine02 scan]# chown app_user:app_user attach
[root@test-machine02 scan]#
[root@test-machine02 scan]# ls -ltr
total 2260
drwx------. 2 root       root         16384 Oct 22  2020 lost+found
drwxrwxrwx. 2 app_user app_user    4096 Dec  9 12:30 Image
drwxrwxrwx. 3 app_user app_user 2293760 Jan 18 10:21 attach
[root@test-machine02 scan]#

Step 6. Start dependent Services in Target Server: Start the dependent services in a new server.

[root@test-machine02 ~]#
[root@test-machine02 ~]# systemctl start smb.service
[root@test-machine02 ~]# systemctl enable smb.service
[root@test-machine02 ~]# systemctl status smb.service
â smb.service - Samba SMB Daemon
   Loaded: loaded (/usr/lib/systemd/system/smb.service; enabled; vendor preset: disabled)
   Active: active (running) since Thu 2021-12-30 06:52:10 +03; 2 weeks 6 days ago
     Docs: man:smbd(8)
           man:samba(7)
           man:smb.conf(5)
 Main PID: 1262 (smbd)
   Status: "smbd: ready to serve connections..."
    Tasks: 5
   CGroup: /system.slice/smb.service
           ââ 1262 /usr/sbin/smbd --foreground --no-process-group
           ââ 1358 /usr/sbin/smbd --foreground --no-process-group
           ââ 1359 /usr/sbin/smbd --foreground --no-process-group
           ââ 1376 /usr/sbin/smbd --foreground --no-process-group
           ââ49991 /usr/sbin/smbd --foreground --no-process-group

Dec 30 06:52:10 test-machine02.saudiacatering.local systemd[1]: Starting Samba SMB Daemon...
Dec 30 06:52:10 test-machine02.saudiacatering.local smbd[1262]: [2021/12/30 06:52:10.896782,  0] ../../lib/util/become_daemon.c:136(daemon_ready)
Dec 30 06:52:10 test-machine02.saudiacatering.local smbd[1262]:   daemon_ready: daemon 'smbd' finished starting up and ready to serve connections
Dec 30 06:52:10 test-machine02.saudiacatering.local systemd[1]: Started Samba SMB Daemon.
[root@test-machine02 ~]#
[root@test-machine02 ~]# systemctl start nfs-server.service
[root@test-machine02 ~]# systemctl enable nfs-server.service
[root@test-machine02 ~]# systemctl status nfs-server.service
â nfs-server.service - NFS server and services
   Loaded: loaded (/usr/lib/systemd/system/nfs-server.service; enabled; vendor preset: disabled)
  Drop-In: /run/systemd/generator/nfs-server.service.d
           ââorder-with-mounts.conf
   Active: active (exited) since Tue 2022-01-18 12:16:07 +03; 23h ago
 Main PID: 208143 (code=exited, status=0/SUCCESS)
    Tasks: 0
   CGroup: /system.slice/nfs-server.service

Jan 18 12:16:07 test-machine02.saudiacatering.local systemd[1]: Starting NFS server and services...
Jan 18 12:16:07 test-machine02.saudiacatering.local systemd[1]: Started NFS server and services.
[root@test-machine02 ~]#

This document is just for learning purpose and always validate in the LAB environment first before applying in the LIVE environment.

Hope so you like this article!
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ISCSI, LINUX, UNIX, UNIX:LINUX

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