Error "Couldn't determine the size of the Storage Vault"

This is a warning only.

Magnus Box checks the size of the Storage Vault in order to see how much data is stored. This information is used for multiple purposes including some health checks (e.g. size should not decrease during an backup) and for enforcing storage quotas.

Most storage destinations (e.g. filesystem / SFTP / ...) do not have any quick way to determine the size of a directory, other than to add up the size of every file within. Magnus Box does cache this size information in-memory when it is generated, and is able to return a stale measurement. However, around a backup job, an up-to-date size measurement is desirable.

Storage Vault size measurement is a necessary, but not critical, part of the backup process. If it fails, the logs shows an alert warning, the backup will proceed, but quota enforcement and the amount that you bill the client may be wrong.