Internet SCSI (iSCSI) is a network protocol s that allows
you to use of the SCSI protocol over TCP/IP networks. It is good alternative to
Fibre Channel-based SANs. You can easily manage, mount and format iSCSI Volume
under Linux. It allows access to SAN storage over Ethernet.
Open-iSCSI Project
Open ISCSI project is a high-performance, transport independent,
multi-platform implementation of iSCSI. Open-iSCSI is partitioned into user and
kernel parts.
Install Required Package
iscsi-initiator-utils RPM package - The iscsi package
provides the server daemon for the iSCSI protocol, as well as the utility
programs used to manage it. iSCSI is a protocol for distributed disk access
using SCSI commands sent over Internet Protocol networks. This package is
available under Redhat Enterprise Linux / CentOS / Fedora Linux and can be
installed using yum command:
# yum install iscsi-initiator-utils
A note about Debian / Ubuntu Linux
If you are using Debian / Ubuntu Linux install open-iscsi package,
enter:
$ sudo apt-get install open-iscsi
iSCSI Configuration
There are three steps needed to set up a system to use iSCSI
storage:
- iSCSI startup using the init script or manual startup. You need to edit and configure iSCSI via /etc/iscsi/iscsid.conf file
- Discover targets.
- Automate target logins for future system reboots.
- You also need to obtain iSCSI username, password and storage server IP address (target host)
Configure iSCSI
Open /etc/iscsi/iscsid.conf with vi text editor:
# vi /etc/iscsi/iscsid.conf
Setup username and
password:
node.session.auth.username = My_ISCSI_USR_NAME
node.session.auth.password = MyPassword
discovery.sendtargets.auth.username =
My_ISCSI_USR_NAME
discovery.sendtargets.auth.password =
MyPassword
Where,
- node.session.* is used to set a CHAP username and password for initiator authentication by the target(s).
- discovery.sendtargets.* is used to set a discovery session CHAP username and password for the initiator authentication by the target(s)
Now start the iscsi service:
# /etc/init.d/iscsi start
Discover targets
Now use iscsiadm command, which is a command-line tool
allowing discovery and login to iSCSI targets, as well as access and management
of the open-iscsi database. If your storage server IP address is 192.168.8.71,
enter:
# iscsiadm -m discovery -t sendtargets -p 192.168.8.71
# /etc/init.d/iscsi
restart
Now there should be a block device under /dev directory. To
obtain new device name, type:
# fdisk -l
or
# tail -f /var/log/messages
Output:
June 27 12:42:20 ora9is2 kernel: Vendor: EQLOGIC Model: 100E-00 Rev: 3.2
June 27 12:42:20 ora9is2 kernel: Type:
Direct-Access ANSI SCSI revision: 05
June 27 12:42:20 ora9is2 kernel: SCSI device sdd: 41963520
512-byte hdwr sectors (21485 MB)
June 27 12:42:20 ora9is2 kernel: sdd: Write Protect is off
June 27 12:42:20 ora9is2 kernel: SCSI device sdd: drive
cache: write through
June 27 12:42:20 ora9is2 kernel: SCSI device sdd: 41963520
512-byte hdwr sectors (21485 MB)
June 27 12:42:20 ora9is2 kernel: sdd: Write Protect is off
June 27 12:42:20 ora9is2 kernel: SCSI device sdd: drive
cache: write through
June 27 12:42:20 ora9is2 kernel: sdd: unknown partition table
June 27 12:42:20 ora9is2 kernel: sd 3:0:0:0: Attached scsi
disk sdd
June 27 12:42:20 ora9is2 kernel: sd 3:0:0:0: Attached scsi
generic sg3 type 0
June 27 12:42:20 ora9is2 kernel: rtc: lost some interrupts
at 2048Hz.
June 27 12:42:20 ora9is2 iscsid: connection0:0 is
operational now
/dev/sdd is my new block device.
Format and Mount iSCSI Volume
You can now partition and create a filesystem on the target
using usual fdisk and mkfs.ext3 commands:
# fdisk /dev/sdd
# mke2fs -j -m 0 -O
dir_index /dev/sdd1
OR
# mkfs.ext3 /dev/sdd1
Tip: If your volume is large size like 1TB, run mkfs.ext3 in
background using nohup:
# nohup mkfs.ext3 /dev/sdd1 &
Mount new partition:
# mkdir /mnt/iscsi
# mount /dev/sdd1
/mnt/iscsi
Mount iSCSI drive automatically at boot time
First make sure iscsi service turned on at boot time:
# chkconfig iscsi on
Open /etc/fstab file
and append config directive:
/dev/sdd1 /mnt/iscsi ext3 _netdev 0 0
Save and close the
file.
Further readings:
Official Open iSCSI documentation
Note that this document comes without warranty of any kind. But every effort
has been made to provide the information as accurate as possible. I welcome
emails from any readers with comments, suggestions, and corrections at
webmaster_at admin@linuxhowto.in
Copyright © 2012 LINUXHOWTO.IN
Copyright © 2012 LINUXHOWTO.IN
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