What is the effect of enabling encryption at rest on backup file sizes?

Enabling encryption at rest impacts backup file sizes significantly as it typically increases them. When data is encrypted, it is transformed into a format that cannot be easily interpreted by unauthorized users. This transformation often adds additional data (metadata) that is necessary for the encryption process. As a result, the overall size of the backup files can increase, and it is not uncommon for this increase to be in the range of 50% to 100%. This means that if the original data was, for instance, 100 MB, the encrypted backup could potentially range from 150 MB to 200 MB, depending on the algorithm used and the nature of the data.

In contrast, options that imply no impact or a decrease in file size do not align with the operational realities of data encryption. Additionally, suggesting that only encrypted files are affected overlooks the fact that enabling encryption applies universally to all data being backed up, regardless of its previous state. Thus, the conclusion drawn regarding the increase in backup file size when encryption at rest is enabled is indeed accurate.