EX300 - iSCSI

0. Online help

server-side / target:

targetcli is one of the most friendly software which provides fantastic UI and on-line help. 

'ls' and 'cd' commands are so helpful. When you "cd" into a path, "help" lists available commands in the current context.

client-side / initiator:

man iscsiadm  [EXAMPLES section]

1. Cheat-sheet

1.1 Server side

# Prepare the backstore partition
parted /dev/vda
>print free
>mkpart primary ....

# in targetcli, create backstore, iqn, lun, acl, portal
targetcli 

# firewall setup
firewall-cmd --permanent --add-rich-rule 'rule family=ipv4 source address=192.168.100.40/32 port port=3260 accept'
firewall-cmd --reload

1.2  Client side

# modify /etc/iscsi/initiatorname.iscsi
InitiatorName=iqn.2001-05.com.example:client

# dicover the iqn
iscsiadm --mode discoverydb --type sendtargets --portal 192.168.100.30 --discover

# login the iqn
iscsiadm --mode node --targetname iqn.2001-05.com.example:server --portal 192.168.100.30:3260 --login

# list targets
iscsiadm --mode node

# check the new iscsi disk/lun
lsblk

# partition the disk
parted /dev/sda

# modify /etc/fstab
blkid # get the UUID of the part
/etc/fstab: UUID="xxxx" /mnt/data xfs defautls 0 0
mount -a

2. Tips

• Create the required back store at the very beginning of the exam.

This task may ask creating a partition / LV as a back store. Storage operations are critical as they may cause the OS failed to boot.

• Don't try to shrink ROOT fs!!!

It is not common that you have to allocate disk space by shrinking rootfs. Try hard to find if there are free spaces in any disk, vg, pv. If it really happens that there is no space except shrinking rootfs, just give up this task.

For extending or shrinking FS/LV, please refer to:

 https://www.linuxexam.net/2019/09/ex300-how-to-resize-ext4-file-system.html

It's much better to pass the exam with losing marks on this task than to fail the exam because of an unbootable system.