iSCSI (Internet Small Computer System Interfac)
iSCSI is Internet SCSI (Small Computer System Interface), an Internet Protocol (IP)-based storage networking standard for linking data storage facilities by carrying SCSI commands over IP networks. iSCSI is used to facilitate data transfers over intranets and to manage storage over long distances. iSCSI makes block devices available via the network. We can mount block devices (disks) across an IP network to local system and then use them like any other block device. iSCSI is a client-server protocol. The server-side is referred to as the 'target,' while the client-side is referred to as the 'initiator.' Both the target and initiator are uniquely identified by a string called the iSCSI Qualified Name (iQN). Initiators come in two varieties: software and hardware. A software initiator is just a driver that handles all requests and pairs the network interfaces driver and the SCSI drivers together to make it work. Using a software initiator any system with an Ethernet card can act as an iSCSI initiator. A hardware initiator is an iSCSI HBA, which is basically just an ethernet card with a SCSI ASIC onboard. Here we are configuring software initiator in RHEL 6.
Packages- scsi-target-utils
Port No- 3260
Daemon- tgtd
Script- /etc/init.d/tgtd
Conf file- /etc/tgt/targets.conf
Configure iSCSI Server Side.
Step-1. Install iSCSI Package-
# yum install scsi-target-utils
Step-2 Configure network with ipaddress and make sure that clients are reachable to the server. By default iSCSI will listen to the port 3260, we have to add necessary rules in iptables to allow iSCSI. Ignore this step if firewall is disabled.
# iptables -I INPUT -p tcp -m tcp --dport 3260 -j ACCEPT
# service iptables save
# service iptables restart
Step-3. (Allocate storage for the LUNs)The iSCSI target service is not dependent on a particular type of exported LUN. The LUNs can be plain files, LVM volumes, or block devices. There is however a performance overhead if using the LVM and/or file system layers as compared to block devices. This example demonstrates the creation of a local partition /dec/sdb1 as iSCSI storage LUN.
Create a Partition 5G.
# fdisk /dev/sdb
Device Boot Start End Blocks Id
System /dev/sdb1 1 391 3140676 83 Linux
# partx -a /dev/sdb
# mkfs.ext4 /dev/sdb1
Step-4. Create a targets..
# vim /etc/tgt/targets.conf
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<target iqn.2014-03.com.ashu:server.test1>
backing-store /dev/dev/sdb1
initiator-address 192.168.0.100 { For incominguser root redhat perticular system access}
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Configure iSCSI Client Side.
Step-1 Install iSCSI package
# yum install iscsi-initiator-utils*
# iscsiadm -m discovery -t
sendtargets -p 192.168.0.254
Starting iscsid: [ OK ]
10.30.32.206:3260,1 iqn.2008-09.com.example:server.target1t
Step-3. To connect iSCSI target
# iscsiadm --mode node --targetname iqn.2014-03.com.ashu:server1.test1 --portal 192.168.0.254:3260 --login
Now iSCSI target is connected from ip 192.168.0.254.
Step- 4. Create a File System..
we can create file system on /ded/sdc1 and use locally
# fdisk -l
# fdisk /dev/sdc
create a +2G partion
:wq
# partx -a /dev/sdc
# mkfs.ext4 /dev/sdc1
#vim /etc/fstab
/dev/sdc1 /mnt ext4 defaults 0 0
:wq
# mount -a
# touch test-1 test-2 test-3 test-4 (Now Create some file in /mnt )
# iscsiadm --mode node --targetname iqn.2011-12.com.example:server1.test1 --portal 192.168.0.254:3260 --logout
#init 6 (Restart System)
#cd /mnt (Again Check it will show your data)
iSCSI is Internet SCSI (Small Computer System Interface), an Internet Protocol (IP)-based storage networking standard for linking data storage facilities by carrying SCSI commands over IP networks. iSCSI is used to facilitate data transfers over intranets and to manage storage over long distances. iSCSI makes block devices available via the network. We can mount block devices (disks) across an IP network to local system and then use them like any other block device. iSCSI is a client-server protocol. The server-side is referred to as the 'target,' while the client-side is referred to as the 'initiator.' Both the target and initiator are uniquely identified by a string called the iSCSI Qualified Name (iQN). Initiators come in two varieties: software and hardware. A software initiator is just a driver that handles all requests and pairs the network interfaces driver and the SCSI drivers together to make it work. Using a software initiator any system with an Ethernet card can act as an iSCSI initiator. A hardware initiator is an iSCSI HBA, which is basically just an ethernet card with a SCSI ASIC onboard. Here we are configuring software initiator in RHEL 6.
Packages- scsi-target-utils
Port No- 3260
Daemon- tgtd
Script- /etc/init.d/tgtd
Conf file- /etc/tgt/targets.conf
Configure iSCSI Server Side.
Step-1. Install iSCSI Package-
# yum install scsi-target-utils
Step-2 Configure network with ipaddress and make sure that clients are reachable to the server. By default iSCSI will listen to the port 3260, we have to add necessary rules in iptables to allow iSCSI. Ignore this step if firewall is disabled.
# iptables -I INPUT -p tcp -m tcp --dport 3260 -j ACCEPT
# service iptables save
# service iptables restart
Step-3. (Allocate storage for the LUNs)The iSCSI target service is not dependent on a particular type of exported LUN. The LUNs can be plain files, LVM volumes, or block devices. There is however a performance overhead if using the LVM and/or file system layers as compared to block devices. This example demonstrates the creation of a local partition /dec/sdb1 as iSCSI storage LUN.
Create a Partition 5G.
# fdisk /dev/sdb
Device Boot Start End Blocks Id
System /dev/sdb1 1 391 3140676 83 Linux
# partx -a /dev/sdb
# mkfs.ext4 /dev/sdb1
Step-4. Create a targets..
# vim /etc/tgt/targets.conf
____________________________________________________________________________________
<target iqn.2014-03.com.ashu:server.test1>
backing-store /dev/dev/sdb1
initiator-address 192.168.0.100 { For incominguser root redhat perticular system access}
____________________________________________________________________________________
Note:
The target attribute requires an iSCSI Qualified Name
(IQN),following is the general format:
iqn.yyyy-mm.reversed.domain.name:OptionalIdentifierText
yyyy-mm represents the
4-digit year and 2-digit month the device was started (for example: 2014-03)
reversed.domain.name is the hosts domain
name in reverse. For example, server1.example.com, in an IQN, becomes
com.example.server1;
OptionalIdentifierText is any text string,
without spaces, that helps the administrator identifies which device.
Step- 5. Restart tgtd services..
# /etc/init.d/tgtd restart;chkconfig tgtd on
Step-6 Check Configuration
# tgt-admin --show
______________________________________________________________________________________
Target 1: iqn.2014-03.com.ashu:server.test1
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
Online: Yes
Removable
media: No
Backing store
type: rdwr
Backing store
path: None
LUN: 1
Type: disk
SCSI ID:
IET 00010001
SCSI SN:
beaf11
Size: 5 GB
Online: Yes
Removable
media: No
Backing store
type: rdwr
Backing store
path: /dev/sdb1
Account information:
ACL information:
ALL Configure iSCSI Client Side.
Step-1 Install iSCSI package
# yum install iscsi-initiator-utils*
Step-2 Discover the target LUN’s exported by server using following
command. It will provide iqn name with of LUN associated with given ip address
Starting iscsid: [ OK ]
10.30.32.206:3260,1 iqn.2008-09.com.example:server.target1t
Note :
-p : it is indicates the address of target server.Step-3. To connect iSCSI target
# iscsiadm --mode node --targetname iqn.2014-03.com.ashu:server1.test1 --portal 192.168.0.254:3260 --login
Now iSCSI target is connected from ip 192.168.0.254.
Step- 4. Create a File System..
we can create file system on /ded/sdc1 and use locally
# fdisk -l
# fdisk /dev/sdc
create a +2G partion
:wq
# partx -a /dev/sdc
# mkfs.ext4 /dev/sdc1
#vim /etc/fstab
/dev/sdc1 /mnt ext4 defaults 0 0
:wq
# mount -a
# touch test-1 test-2 test-3 test-4 (Now Create some file in /mnt )
# iscsiadm --mode node --targetname iqn.2011-12.com.example:server1.test1 --portal 192.168.0.254:3260 --logout
#init 6 (Restart System)
#cd /mnt (Again Check it will show your data)
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