What happens as storage fills to the limit of Node 1 the primary?

Hello Bill, 

By default, Acronis cyber infrastructure  will balance the load between the storage nodes added to the cluster to make sure storage utilization will be equal. Based on the following design, we recommend all storage nodes to have exactly the same storage space assigned (same number and size of disks equally distributed between storage nodes is recommended to get better storage redundancy).

if storage utilization reached 100% on the Primary node, all CSes will be marked as 'failed' (out of space). You would need to add additional storage disks to the Node1 so the CSes will be rebalanced and node will be operational.

With a single node down, you have the following options (depending on how storage the storage policy is configured):

1) In case of storage 'Redundancy by replication'
  - With one node down, cluster will be still be working as expected (R/W operations won't be suspended)

 2) In case of storage 'Redundancy by erasure-coding' 

 - 1+0 (no redundancy) - Storage will be offline and no further Backup/Recovery operations will be allowed
 - 1+2 - Storage will be still accepting new backups and working as expected (R/W operation won't be suspended)
 - 2+1 - Storage will not accept new backups, but you will be still able to restore servers using the recovery points ( only Write operation will be suspended).