Situation: The client has Veeam backup to back up all their VMs on Microsoft Hyper-V. The backup failed with this error: Unable to allocate memory for storage metadata bank.
Resolution 1: It could be physical server low RAM. Please refer to this article for RAM requirement.
Resolution 2: If the RAM is not the issue, restarting Veeam services may fix the problem.
Resolution 3: Check the status of Windows update. If there is any windows update installed or pending for restart, please do so.
