Client Called (ISCSI- Initiator) ISCSI Storage Devices (Targets) remote server.
IQN – ISCSI Qualified Name – iqn.2014-06.local.labs.infra:disk
ISCSI TARGE CONFIGURATION
1.#yum install iscsi-target-utils
2.Vim /etc/tgt/target.conf
<target iqn.2014-06.local.labs.infra:disk1>
backing –store /dev/sdb
</target>
<target iqn.2014-06.local.labs.infra:disk2>
Backing-storge /dev/sdc
</target>
Iqn – iscsi Qualified Namebacking –store /dev/sdb
</target>
<target iqn.2014-06.local.labs.infra:disk2>
Backing-storge /dev/sdc
</target>
3. /etc/init.d/tgtd start
4.# tgt-admin -s (List out the LUN)
ISCSI INITATOR
1)Discover ISCSI TARGET
#iscsiadm –m discoverdb –t sendtargets –portal ISCSITARGETIP:3260 –discover
10.154.1.180:3260,1 iqn.2013-03.local.labs.infra:disk110.154.1.180:3260,1 iqn.2013-03.local.labs.infra:disk2
2) Login to the ISCSI TARGET
#iscsiadm –m node –portal ISCSITARGETIP:3260 –T iqn.2013-03.local.labs.infra:disk1 –l
# iscsiadm -m node –portal ISCSITARGETIP:3260 –T iqn.2013-03.local.labs.infra:disk2 –l
3) After iscsi login,it will list out list of devices client system.# iscsiadm -m node –portal ISCSITARGETIP:3260 –T iqn.2013-03.local.labs.infra:disk2 –l
#fidsk -l (Actually it has only two device due to the two physical network it will show four devices - 2 disk * 2 Physical network = 4 devices)
Disk /dev/sdb: 2147 MB, 2147483648 bytes
Disk /dev/sdc: 2147 MB, 2147483648 bytes
Disk /dev/sdd: 2147 MB, 2147483648 bytes
Disk /dev/sde: 2147 MB, 2147483648 bytes
DEVICE MAPPER MULTIPATH
1)DM-Multipath – More than one path to the shared Storage.
2)Ability of the server communicate with same physical (or) logical storage block device across MULTIPLE PHYSCIAL path between HOST BUS ADAPTER in the server and STORAGE CONTROLLER for the device. Typically Fiber channel (or) ISCSI in SAN environment.
3)Why Multipath : Avoid single point of failure(Redundancy) and load balancing.
HBA failure(2 HBA)
FC cable failure(2 FC cable)
SAN switch failure(2 SAN Switch)
Array controller port failure
Real Time - Storage Multipath Configuration.
1)Each server has 2 FC Adapter
2)Have Two SAN Switch
3)Storage Controller have 4 FC Adapter
3)/etc/multipath.conf Configuration file creation
# cp /usr/share/doc/device-mapper-multipath-0.4.9/multipath.conf /etc/
#cat /etc/multipath.conf.
Under
defaults
prio alua to change const like.
defaults {
udev_dir /dev
polling_interval 10
path_selector "round-robin 0"
path_grouping_policy multibus
getuid_callout "/lib/udev/scsi_id --whitelisted --device=/dev/%n --replace-whitespace"
prio const
path_checker readsector0
rr_min_io 100
max_fds 8192
rr_weight priorities
failback immediate
no_path_retry fail
user_friendly_names no
}
4)# /etc/init.d/multipathd restartudev_dir /dev
polling_interval 10
path_selector "round-robin 0"
path_grouping_policy multibus
getuid_callout "/lib/udev/scsi_id --whitelisted --device=/dev/%n --replace-whitespace"
prio const
path_checker readsector0
rr_min_io 100
max_fds 8192
rr_weight priorities
failback immediate
no_path_retry fail
user_friendly_names no
}
# ls -l /dev/mapper/* /dev/dm-*
brw-rw---- 1 root disk 253, 0 Jun 24 14:58 /dev/dm-0
brw-rw---- 1 root disk 253, 2 Jun 24 14:37 /dev/dm-1
lrwxrwxrwx 1 root root 7 Jun 24 14:37 /dev/mapper/1IET_00010001 -> ../dm-1 lrwxrwxrwx 1 root root 7 Jun 24 14:37 /dev/mapper/1IET_00020001 -> ../dm-0 crw-rw---- 1 root root 10, 58 Jun 24 12:30 /dev/mapper/control
Error & Solution
# iscsiadm -m discoverydb -t st --portal 10.154.1.180:3260 --discover
iscsiadm: cannot make connection to 10.154.1.180: No route to host
iscsiadm: cannot make connection to 10.154.1.180: No route to host
SOLUTION: 10.154.1.180 Add The Input chain 3260 as ACCEPT in iptables.
#iptables -I INPUT -p tcp --dport 3260 -j ACCEPT.
Then the problem got solved.TO ISCSI Configuration In EMC Storage Refer This PDF LINK.
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