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How To Connect And Mount iSCSI Onto Linux Servers

How To Connect And Mount iSCSI Onto Linux Servers

TLDR;

Discovering targets in iSCSI server:

iscsiadm –mode discovery -t sendtargets –portal 192.168.1.141 192.168.1.141:3260,1 iqn.2006-01.com.openfiler:tsn.d625a0d9cb77

login with the iSCSI LUN:

[root@machine1 ~]# iscsiadm --mode node --targetname  iqn.2006-01.com.openfiler:tsn.d625a0d9cb77  --portal 192.168.1.141 --login

Mount the iscsi target:

mount /dev/sdb2 /mnt

Disconnect/remove  target:

umount /mnt

[root@machine1 ~]# iscsiadm –mode node –targetname  iqn.2006-01.com.openfiler:tsn.d625a0d9cb77  –portal 192.168.1.141 –logout

Optionally delete the record from the database:

iscsiadm -m node -o delete -T iqn.2006-01.com.openfiler:tsn.d625a0d9cb77 –portal 192.168.1.141:3260

 

Details:

iscsi Server: 192.168.1.141
Centos Server: 192.168.1.137

The commands bellow should be working in other Linux distro.

First, install some needed packages.

Centos :

yum -y install iscsi-initiator-utils
service iscsid start
service iscsi start

Ubuntu:

sudo apt-get install open-iscsi

Opensuse

# zypper install open-iscsi

Discovering targets in iSCSI server:

 [root@machine1 ~]# iscsiadm --mode discovery -t sendtargets --portal 192.168.1.141
192.168.1.141:3260,1 iqn.2006-01.com.openfiler:tsn.d625a0d9cb77

Trying to login with the iSCSI LUN:

[root@machine1 ~]# iscsiadm --mode node --targetname  iqn.2006-01.com.openfiler:tsn.d625a0d9cb77  --portal 192.168.1.141 --login
 Logging in to [iface: default, target: iqn.2006-01.com.openfiler:tsn.d625a0d9cb77, portal: 192.168.1.141,3260] (multiple)
 Login to [iface: default, target: iqn.2006-01.com.openfiler:tsn.d625a0d9cb77, portal: 192.168.1.141,3260] successful.
 [root@machine1 ~]#

With this command is responsible of the update of  iSCSI targets database for the files located in /var/lib/iscsi/ :

[root@machine1 ~]# cat /var/lib/iscsi/send_targets/192.168.1.141,3260/st_config
 # BEGIN RECORD 6.2.0-873.10.el6
 discovery.startup = manual
 discovery.type = sendtargets
 discovery.sendtargets.address = 192.168.1.141
 discovery.sendtargets.port = 3260
 discovery.sendtargets.auth.authmethod = None
 discovery.sendtargets.timeo.login_timeout = 15
 discovery.sendtargets.use_discoveryd = No
 discovery.sendtargets.discoveryd_poll_inval = 30
 discovery.sendtargets.reopen_max = 5
 discovery.sendtargets.timeo.auth_timeout = 45
 discovery.sendtargets.timeo.active_timeout = 30
 discovery.sendtargets.iscsi.MaxRecvDataSegmentLength = 32768
 # END RECORD
 [root@machine1 ~]#

Now check if the disk add to your machine

[root@machine1 ~]# fdisk  -l
Disk /dev/sda: 17.8 GB, 17791238144 bytes
 255 heads, 63 sectors/track, 2162 cylinders
 Units = cylinders of 16065 * 512 = 8225280 bytes
 Sector size (logical/physical): 512 bytes / 512 bytes
 I/O size (minimum/optimal): 512 bytes / 512 bytes
 Disk identifier: 0x000a0b90
Device Boot      Start         End      Blocks   Id  System
 /dev/sda1   *           1        1275    10240000   83  Linux
 /dev/sda2            1275        1913     5120000   8e  Linux LVM
 /dev/sda3            1913        2066     1228800   82  Linux swap / Solaris
Disk /dev/mapper/vg_machine1-LogVol01: 209 MB, 209715200 bytes
 255 heads, 63 sectors/track, 25 cylinders
 Units = cylinders of 16065 * 512 = 8225280 bytes
 Sector size (logical/physical): 512 bytes / 512 bytes
 I/O size (minimum/optimal): 512 bytes / 512 bytes
 Disk identifier: 0x00000000
Disk /dev/mapper/vg_machine1-LogVol00: 2097 MB, 2097152000 bytes
 255 heads, 63 sectors/track, 254 cylinders
 Units = cylinders of 16065 * 512 = 8225280 bytes
 Sector size (logical/physical): 512 bytes / 512 bytes
 I/O size (minimum/optimal): 512 bytes / 512 bytes
 Disk identifier: 0x00000000
Disk /dev/sdb: 369 MB, 369098752 bytes
 12 heads, 59 sectors/track, 1018 cylinders
 Units = cylinders of 708 * 512 = 362496 bytes
 Sector size (logical/physical): 512 bytes / 512 bytes
 I/O size (minimum/optimal): 512 bytes / 512 bytes
 Disk identifier: 0x00000000
[root@machine1 ~]#

Create file system in this disk (for new iscsi disk only)

[root@machine1 ~]# fdisk  /dev/sdb
 Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel
 Building a new DOS disklabel with disk identifier 0x41c55bb7.
 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): 2
 First cylinder (1-1018, default 1):
 Using default value 1
 Last cylinder, +cylinders or +size{K,M,G} (1-1018, default 1018):
 Using default value 1018
Command (m for help): w
 The partition table has been altered!
Calling ioctl() to re-read partition table.
 Syncing disks.

and

[root@machine1 ~]# mkfs.ext4 /dev/sdb2
 mke2fs 1.41.12 (17-May-2010)
 Filesystem label=
 OS type: Linux
 Block size=1024 (log=0)
 Fragment size=1024 (log=0)
 Stride=0 blocks, Stripe width=0 blocks
 90112 inodes, 360340 blocks
 18017 blocks (5.00%) reserved for the super user
 First data block=1
 Maximum filesystem blocks=67633152
 44 block groups
 8192 blocks per group, 8192 fragments per group
 2048 inodes per group
 Superblock backups stored on blocks:
 8193, 24577, 40961, 57345, 73729, 204801, 221185
Writing inode tables: done
 Creating journal (8192 blocks): done
 Writing superblocks and filesystem accounting information: done
This filesystem will be automatically checked every 37 mounts or
 180 days, whichever comes first.  Use tune2fs -c or -i to override.

Prepare the directory to mount the disk.

[root@machine1 ~]#[root@machine1 ~]# mkdir  /iscsi-openfiler
 [root@machine1 ~]# mount  -t ext4 /dev/sdb2  /iscsi-openfiler/
 [root@machine1 ~]# df -h
 Filesystem            Size  Used Avail Use% Mounted on
 /dev/sda1             9.7G  2.4G  6.9G  26% /
 tmpfs                 751M     0  751M   0% /dev/shm
 /dev/mapper/vg_machine1-LogVol00
 2.0G   35M  1.8G   2% /home
 /dev/mapper/vg_machine1-LogVol01
 194M  5.6M  179M   4% /tmp
 /dev/sdb2             341M   11M  314M   4% /iscsi-openfiler

Please add this to mount the net drive with Linux start.
add this to /etc/fstab.

/dev/sdb2  /iscsi-openfiler   ext4 _netdev,rw 0 0

and

chkconfig  netfs  on
chkconfig  iscsi on

There are three ways to disable or delete an iSCSI target.

First, to disable an iSCSI target:

# iscsiadm --m node -T iqn.2006-01.com.openfiler:tsn.d625a0d9cb77 --portal 192.168.1.141:3260 -u

Second, it is possible to delete the target’s record ID:/p>

# iscsiadm -m node -o delete -T iqn.2006-01.com.openfiler:tsn.d625a0d9cb77 --portal 192.168.1.141:3260

Thirdly, stop the iSCSI service.

Source: How To Connect And Mount iSCSI Onto Linux Servers | Unixmen