Why OpenNebula forces me to choose a SYSTEM_DS?

My question is in regards of this error:

[SCHED][D]: VM 17: Datastore 0 filtered out. It does not fulfill SCHED_DS_REQUIREMENTS.

I just want to point out that:

  1. this wasn’t a requirement in v4.0 …
  2. And for those who also receive this error and don’t know what to do - simply assign to your cluster the DS with ID = 0 ( should have a name=“system” and a type=“SYSTEM_DS” )

I have 5 datastores,

ID 0 = SYSTEM_DS type
ID 101 = qcow2ssh type 

I have a cluster that I’ve assigned only the ID=101 DS, because that’s similar to what I currently have in the old server with v4.0…
Then I receive the error listed above, which due to this error the VM never gets created …

So my questions are:

  • who requested this requirement that DS=0 must exists ? I didn’t. so how can I get rid of it ? or if someone can tell me why do I even need it/what’s the benefit of having it vs not having it ?
  • If I have two clusters now, how can I assign the system DS to both of these clusters ? now I need to create for every cluster its own “SYSTEM_DS” ? ( when I enter the DS screen - I can choose only one cluster )