When a torrent download is interrupted, the client software needs to verify the integrity of the partially downloaded files before resuming. This process involves comparing the existing data against the torrent’s metadata to ensure data consistency and prevent corruption. For example, if a power outage occurs during a download, the client will, upon restart, scan the incomplete files to determine which pieces are valid and which need to be re-downloaded.
This verification process is crucial for maintaining download integrity. By confirming the validity of existing data, the client avoids wasting bandwidth by re-downloading already complete segments. This saves time and resources, especially with large files. Furthermore, it prevents corrupted files from being assembled, ensuring the final downloaded content is usable. This functionality has been a core component of torrent clients since their early development, contributing significantly to their reliability.
