A virtual desktop user is in the process of saving a file when the UPS connected to the VM host server fails and the server powers off. After replacing the failed UPS, the user reports that the file…

RAID controllers use a battery-backed write cache (BBWC) to temporarily store write operations before they are committed to disk. If the cache battery has failed, the controller cannot preserve in-flight writes during a power loss event, causing recently written data such as the file being saved to be lost when the UPS and server powered off.

An improper disk partition would cause persistent issues with volume accessibility or filesystem errors, not a data loss event specifically tied to a sudden power outage.

Insufficient disk space would prevent new writes from occurring at all and would generate an error before the save operation, not cause partial data loss during a power failure.

A storage array rebuild is a recovery process that occurs after a drive failure and would not directly cause recent in-memory writes to a file to be lost during a power-off event.