Configuring an iscsi volume for RHV usage

Fran Garcia — Tue, 29 Aug 2017 06:23:07 GMT

This is a cheatsheet to quickly configure storage and export it as an iSCSI volume using RHEL7 targetcli and have it configured under RHV. This is by no means a production configuration as your RHEL7 system might become a single point of failure, but it convers nicely building a home lab or test environment.

Just for clarity, a quick reminder of iSCSI concepts:

An iSCSI target provides some storage (here called server),
An iSCSI initiator uses this available storage (here called client).

Prerequisites

Configure server's storage

You can configure several types of backends, and for me the most versatile is using LVM's Logical Volumes. You'll need to create your volumes in advance, for example:

lvcreate yourVG -n yourLV1 -L 50G

Install software

Install the targetcli RPM:

yum install -y targetcli

Enable the target daemon (NOT targetd)

systemctl enable --now target.service

Gather RHV configuration

You'll need to gather the following information from RHV:

IQN (iSCSI identifier)

Configure and enable iSCSI

targetcli provides a very simple way to create iscsi targets once you understand how it works. Namely what needs to be done is:

Add your backend devices. This is where you add into targetcli's control the LVM devices created in previous steps
Create an IQN target. This is a collection of luns shared to the same system(s) under the same group. It is used later to apply ACLs so only certain hosts can use certain LUNs.
Add LUNs into your IQN target. After creating your IQN target, you need to add the backstore devices so they're shared via iSCSI.
Add ACLs into your IQN target. Unless configured otherwise, LUNs are not visible to systems unless they're added into the right ACL.

Here is a dump on how all this can be accomplished with targetcli:

Add storage into RHV

foo