How to create and setup LUNs using LVM
To create and setup LUNs using LVM on RHEL/CentOS/Fedora
LUN is a Logical Unit Number that shared from the iSCSI Storage Server. The iSCSI target server physical drive shares its drive to initiate over TCP/IP network. It form a large storage as SAN (Storage Area Network) with a collection of drives. LUNs are defined in LVM as per space availability in real environment. Creating LUNs using LVM is explained in this article.
Importance of LUN
- It is used for storage purpose.
- It is used to install Operating systems and also in Clusters, Virtual servers, SAN etc.
To Create LUNs using LVM in iSCSI Target Server
Using ' fdisk -l' command, find out the list of drives in every partitions on the system.
[root@linuxhelp ~]# fdisk -l
Disk /dev/sda: 21.5 GB, 21474836480 bytes, 41943040 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: 0x000b5211
Device Boot Start End Blocks Id System
/dev/sda1 * 2048 1026047 512000 83 Linux
/dev/sda2 1026048 5122047 2048000 82 Linux swap / Solaris
/dev/sda3 5122048 41943039 18410496 83 Linux
Disk /dev/sdb: 42.9 GB, 42949672960 bytes, 83886080 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 byt
Creation of LVM Drive for LUNs
Use /dev/sdb drive for creating a LVM.
Now Partition the drive using the following fdisk command,
[root@linuxhelp ~]# fdisk /dev/sdb Welcome to fdisk (util-linux 2.23.2). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Device does not contain a recognized partition table Building a new DOS disklabel with disk identifier 0xb4237527. Command (m for help): n Partition type: p primary (0 primary, 0 extended, 4 free) e extended Select (default p): p Partition number (1-4, default 1): First sector (2048-83886079, default 2048): Using default value 2048 Last sector, +sectors or +size{K,M,G} (2048-83886079, default 83886079): +15G Partition 1 of type Linux and of size 15 GiB is set Command (m for help): t Selected partition 1 Hex code (type L to list all codes): 8e Changed type of partition ' Linux' to ' Linux LVM' Command (m for help): p Disk /dev/sdb: 42.9 GB, 42949672960 bytes, 83886080 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: 0xb4237527 Device Boot Start End Blocks Id System /dev/sdb1 2048 31459327 15728640 8e Linux LVM Command (m for help): w The partition table has been altered! Calling ioctl() to re-read partition table. Syncing disks.
Creation of Logical Volume for LUNs
Create Physical volume using ‘ pvcreate’ command.
[root@linuxhelp ~]# pvcreate /dev/sdb1
Physical volume " /dev/sdb1" successfully created
Next create a Volume group with name of iSCSI.
[root@linuxhelp ~]# vgcreate vg1 /dev/sdb1
Volume group " vg1" successfully created
Define 6 Logical Volumes for 6 LUNs in our iSCSI Target server.
[root@linuxhelp ~]# lvcreate -L 2G -n lv1 vg1 Logical volume " lv1" created [root@linuxhelp ~]# lvcreate -L 2G -n lv2 vg1 Logical volume " lv2" created [root@linuxhelp ~]# lvcreate -L 2G -n lv3 vg1 Logical volume " lv3" created [root@linuxhelp ~]# lvcreate -L 2G -n lv4 vg1 Logical volume " lv4" created [root@linuxhelp ~]# lvcreate -L 2G -n lv5 vg1 Logical volume " lv5" created [root@linuxhelp ~]# lvcreate -L 2G -n lv6 vg1 Logical volume " lv6" created
Confirm it by listing the Physical volume, Volume group and logical volumes.
[root@linuxhelp ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb1 vg1 lvm2 a-- 15.00g 3.00g [root@linuxhelp ~]# vgs VG #PV #LV #SN Attr VSize VFree vg1 1 6 0 wz--n- 15.00g 3.00g [root@linuxhelp ~]# lvs LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert lv1 vg1 -wi-a----- 2.00g lv2 vg1 -wi-a----- 2.00g lv3 vg1 -wi-a----- 2.00g lv4 vg1 -wi-a----- 2.00g lv5 vg1 -wi-a----- 2.00g lv6 vg1 -wi-a----- 2.00g
To Define LUNs in Target Server
Run the following command to create the LUNs in the target server.
[root@linuxhelp ~]# targetcli targetcli shell version 2.1.fb41 Copyright 2011-2013 by Datera, Inc and others. For help on commands, type ' help' . /> /backstores/block create iscsi_block1 /dev/vg1/lv1 Created block storage object iscsi_block1 using /dev/vg1/lv1. /> /backstores/block create iscsi_block2 /dev/vg1/lv2 Created block storage object iscsi_block2 using /dev/vg1/lv2. /> /backstores/block create iscsi_block3 /dev/vg1/lv3 Created block storage object iscsi_block3 using /dev/vg1/lv3. /> /backstores/block create iscsi_block4 /dev/vg1/lv4 Created block storage object iscsi_block4 using /dev/vg1/lv4. /> /backstores/block create iscsi_block5 /dev/vg1/lv5 Created block storage object iscsi_block5 using /dev/vg1/lv5. /> /backstores/block create iscsi_block6 /dev/vg1/lv6 Created block storage object iscsi_block6 using /dev/vg1/lv6. /> /iscsi create iqn.2015-06.com.linuxhelp.server Created target iqn.2015-06.com.linuxhelp.server. Created TPG 1. Global pref auto_add_default_portal=true Created default portal listening on all IPs (0.0.0.0), port 3260. /> /iscsi/iqn.2015-06.com.linuxhelp.server/tpg1/acls create iqn.2015-06.com.linuxhelp.client Created Node ACL for iqn.2015-06.com.linuxhelp.client /> /iscsi/iqn.2015-06.com.linuxhelp.server/tpg1/luns create /backstores/block/iscsi_block1 Created LUN 0. Created LUN 0-> 0 mapping in node ACL iqn.2015-06.com.linuxhelp.client /> /iscsi/iqn.2015-06.com.linuxhelp.server/tpg1/luns create /backstores/block/iscsi_block2 Created LUN 1. Created LUN 1-> 1 mapping in node ACL iqn.2015-06.com.linuxhelp.client /> /iscsi/iqn.2015-06.com.linuxhelp.server/tpg1/luns create /backstores/block/iscsi_block3 Created LUN 2. Created LUN 2-> 2 mapping in node ACL iqn.2015-06.com.linuxhelp.client /> /iscsi/iqn.2015-06.com.linuxhelp.server/tpg1/luns create /backstores/block/iscsi_block4 Created LUN 3. Created LUN 3-> 3 mapping in node ACL iqn.2015-06.com.linuxhelp.client /> /iscsi/iqn.2015-06.com.linuxhelp.server/tpg1/luns create /backstores/block/iscsi_block5 Created LUN 4. Created LUN 4-> 4 mapping in node ACL iqn.2015-06.com.linuxhelp.client /> /iscsi/iqn.2015-06.com.linuxhelp.server/tpg1/luns create /backstores/block/iscsi_block6 Created LUN 5. Created LUN 5-> 5 mapping in node ACL iqn.2015-06.com.linuxhelp.client /> ls o- / ................................................................................... [...] o- backstores ........................................................................ [...] | o- block ............................................................ [Storage Objects: 6] | | o- iscsi_block1 ........................... [/dev/vg1/lv1 (2.0GiB) write-thru activated] | | o- iscsi_block2 ........................... [/dev/vg1/lv2 (2.0GiB) write-thru activated] | | o- iscsi_block3 ........................... [/dev/vg1/lv3 (2.0GiB) write-thru activated] | | o- iscsi_block4 ........................... [/dev/vg1/lv4 (2.0GiB) write-thru activated] | | o- iscsi_block5 ........................... [/dev/vg1/lv5 (2.0GiB) write-thru activated] | | o- iscsi_block6 ........................... [/dev/vg1/lv6 (2.0GiB) write-thru activated] | o- fileio ........................................................... [Storage Objects: 0] | o- pscsi ............................................................ [Storage Objects: 0] | o- ramdisk .......................................................... [Storage Objects: 0] o- iscsi ...................................................................... [Targets: 1] | o- iqn.2015-06.com.linuxhelp.server ............................................ [TPGs: 1] | o- tpg1 ......................................................... [no-gen-acls, no-auth] | o- acls .................................................................... [ACLs: 1] | | o- iqn.2015-06.com.linuxhelp.client ............................... [Mapped LUNs: 6] | | o- mapped_lun0 .................................... [lun0 block/iscsi_block1 (rw)] | | o- mapped_lun1 .................................... [lun1 block/iscsi_block2 (rw)] | | o- mapped_lun2 .................................... [lun2 block/iscsi_block3 (rw)] | | o- mapped_lun3 .................................... [lun3 block/iscsi_block4 (rw)] | | o- mapped_lun4 .................................... [lun4 block/iscsi_block5 (rw)] | | o- mapped_lun5 .................................... [lun5 block/iscsi_block6 (rw)] | o- luns .................................................................... [LUNs: 6] | | o- lun0 ........................................ [block/iscsi_block1 (/dev/vg1/lv1)] | | o- lun1 ........................................ [block/iscsi_block2 (/dev/vg1/lv2)] | | o- lun2 ........................................ [block/iscsi_block3 (/dev/vg1/lv3)] | | o- lun3 ........................................ [block/iscsi_block4 (/dev/vg1/lv4)] | | o- lun4 ........................................ [block/iscsi_block5 (/dev/vg1/lv5)] | | o- lun5 ........................................ [block/iscsi_block6 (/dev/vg1/lv6)] | o- portals .............................................................. [Portals: 1] | o- 0.0.0.0:3260 ............................................................... [OK] o- loopback ................................................................... [Targets: 0] /> saveconfig Last 10 configs saved in /etc/target/backup. Configuration saved to /etc/target/saveconfig.json /> exit Global pref auto_save_on_exit=true Last 10 configs saved in /etc/target/backup. Configuration saved to /etc/target/saveconfig.json
Now restart the target services to see the changes.
[root@linuxhelp ~]# systemctl restart target [root@linuxhelp ~]# targetcli targetcli shell version 2.1.fb41 Copyright 2011-2013 by Datera, Inc and others. For help on commands, type ' help' . /> ls o- / ................................................................................... [...] o- backstores ........................................................................ [...] | o- block ............................................................ [Storage Objects: 6] | | o- iscsi_block1 ........................... [/dev/vg1/lv1 (2.0GiB) write-thru activated] | | o- iscsi_block2 ........................... [/dev/vg1/lv2 (2.0GiB) write-thru activated] | | o- iscsi_block3 ........................... [/dev/vg1/lv3 (2.0GiB) write-thru activated] | | o- iscsi_block4 ........................... [/dev/vg1/lv4 (2.0GiB) write-thru activated] | | o- iscsi_block5 ........................... [/dev/vg1/lv5 (2.0GiB) write-thru activated] | | o- iscsi_block6 ........................... [/dev/vg1/lv6 (2.0GiB) write-thru activated] | o- fileio ........................................................... [Storage Objects: 0] | o- pscsi ............................................................ [Storage Objects: 0] | o- ramdisk .......................................................... [Storage Objects: 0] o- iscsi ...................................................................... [Targets: 1] | o- iqn.2015-06.com.linuxhelp.server ............................................ [TPGs: 1] | o- tpg1 ......................................................... [no-gen-acls, no-auth] | o- acls .................................................................... [ACLs: 1] | | o- iqn.2015-06.com.linuxhelp.client ............................... [Mapped LUNs: 6] | | o- mapped_lun0 .................................... [lun0 block/iscsi_block1 (rw)] | | o- mapped_lun1 .................................... [lun1 block/iscsi_block2 (rw)] | | o- mapped_lun2 .................................... [lun2 block/iscsi_block3 (rw)] | | o- mapped_lun3 .................................... [lun3 block/iscsi_block4 (rw)] | | o- mapped_lun4 .................................... [lun4 block/iscsi_block5 (rw)] | | o- mapped_lun5 .................................... [lun5 block/iscsi_block6 (rw)] | o- luns .................................................................... [LUNs: 6] | | o- lun0 ........................................ [block/iscsi_block1 (/dev/vg1/lv1)] | | o- lun1 ........................................ [block/iscsi_block2 (/dev/vg1/lv2)] | | o- lun2 ........................................ [block/iscsi_block3 (/dev/vg1/lv3)] | | o- lun3 ........................................ [block/iscsi_block4 (/dev/vg1/lv4)] | | o- lun4 ........................................ [block/iscsi_block5 (/dev/vg1/lv5)] | | o- lun5 ........................................ [block/iscsi_block6 (/dev/vg1/lv6)] | o- portals .............................................................. [Portals: 1] | o- 0.0.0.0:3260 ............................................................... [OK] o- loopback ................................................................... [Targets: 0] /> exit Global pref auto_save_on_exit=true Last 10 configs saved in /etc/target/backup. Configuration saved to /etc/target/saveconfig.json
Q
How to mirror LVM partition?
A
By using this "lvconvert" command you can mirror the LVM partition.
Q
What is LUNS? I need to know exact functionality of that?
A
LUN is a Logical Unit Number that shared from the iSCSI Storage Server.
Q
Service is not getting started it shows certain errors?
A
please post your errors or else if you wanna troubleshoot please go through /var/log/messages
Q
Will this work on Centos 7 ?
A
Yes it will work on RHEL/Centos/Oracle linux
Q
Crisp explanation
A
Thank you !!