Rhev – Red Hat Enterprise Virtualization 3.0 – stores data on special areas named Storage Domains (aka SD). An iscsi SD has lun attached – which is usually a Logical Volume (aka LV).

With current releases, you can’t grow a SD modifying the underlying LVs. This is probably due to the complex structure of the Storage Pool Manager which coordinates storage access from various hypervisors.

Let’s grow our “my_iscsi”. If we’re lucky we can do:
1- edit it in the rhev-manager interface;
2- add another LUN/Target to it.

In case the target lun exists but the rhev-manager can’t discover it, we may need to rediscover it trying to create a new storage domain. So:
a- try to create a new iscsi storage domain (don’t save it!);
b- discover for the missing target/lun so that rhev-manager is now aware of it;
c- close the create menu WITHOUT saving.

Now let’s re-select the “my_iscsi” and edit and we should see the new target! Once added to the SD click on “save” and we’re done.