After upgrading Veeam backup from 9 >9.5 start getting production datastore getting low alerts even thought we have about 45GB free space. prior to upgrade had 42GB. Any idea?
With only ~42 GB free it might also be a good idea to consider increasing the storage space, or migrating some VMs to other datastores.
Veeam - like other backup applications - creates snapshots for its backups, and in case one of them cannot be deleted, you may be in trouble if the datastore runs out of disk space!
You should at least enable notification for the Datsatore usage alarm.