I have recently encountered an issue where one of the databases suddenly moved to Recovery Pending status.
I came to know this error when an SSRS report returned the error below:
Database [dbname] cannot be opened due to inaccessible files or insufficient memory or disk space.
I checked the database and it is in Recovery Pending status. Recovery Pending means that recovery cannot be started. Until the cause is fixed, recovery cannot run and the database cannot come online. I then checked the drives in the server and one of the drives is down and not accessible.
We brought the drive back online but still the status of the database is not changed. I had to restart the SQL Server service manually and the database is automatically recovered.