During the process of encrypting an 32GB, exFAT formatted flash drive (32K cluster size), the encryption process would randomly stop, with an error in the Event Viewer such as "unable to flush metadata", or "delayed write failed".
This almost seemed to indicate that the drive was physically disconnected. However, it still appears in
- Device Manager
- Safely Remove Hardware list (with the drive letter)
- My Computer (without a drive letter, and unbrowsable, saying the device is missing)
It does not appear in
- Disk Management console
This happened twice, the only way to resolve it being to remove and reinsert the drive, at which point encryption picked up and carried on again. After two such re-inserts, encryption finally completed.
This disk has never had any issues with disconnects or failures on this machine in the past, before BitLocker was introduced. What is going on here?
Large writes would not seem to be the problem, as this drive has on a couple occasions sustained writes of files exceeding 30GB in size without incident.
So far, I have not been able to reproduce the problem again. Successive decryption/re-encryption cycles encountered no errors.