I see, that in Opennebula 5 is block lvm removed and advertized to use fs_lvm.
What I read and understand is:
All images are stored in system datastore and when vm is instancianed, image is cloned from system ds to images ds. But what about persistent images? I have majority of persistant images… where they are stored? In system datastore and never copied to image ds? or? My system datastore has just 20GB and images datastore 7TB.
When you end a VM (“terminate” in 5.0) the disks that come from persistent images will be copied back to the image datastore.
Images are always stored as files in the image datastore, when you instantiate them they are dumped into a new LV in the LVM, and then copied back to the file in the image datastore (and the LV deleted).
So, the answer is that it’s still very similar to the original block lvm, except that the source images are stored as files, and not as LVs, but when they’re in execution, just like in block lvm, they are stored in LVs.
By the way, you can still use the block lvm from the addon repository: