An 80 GB folder is going to a drive with 90 GB free. That sounds sufficient, but extraction, conversion, or extra intermediate copies may need more room. Individual-file limits can matter too. Before starting a long transfer, check the intended process as a whole rather than relying on one capacity figure.
Measure source and destination correctly
Calculate the size of the complete selection, including subfolders, and wait for the calculation to finish. For cloud placeholders, reported file size and local disk usage may differ. A download needs room for the full contents, not just the current local footprint.
Check the actual destination drive and, for cloud services, the quota of the correct account. Free computer storage is different from available online storage. A synchronized folder can encounter both limits. Identify which copies will exist simultaneously during the operation.
Allow for file limits and working space
A large individual file can exceed the file system's limit even when the drive has enough total room. FAT32 is a common example. Before changing file systems, check compatibility with the devices you need and back up existing contents. Formatting should not be an impulsive response to an unclear error.
A ZIP download may require space for both the archive and its extracted contents. A video export adds a new output alongside the sources. Allow for these actual steps rather than choosing an arbitrary reserve. Temporary processing may also consume space on the system drive.
Transfer in a controlled way
Close unnecessary large tasks and keep the computer adequately powered during transfer. For very large collections, logical batches can make errors easier to track. Keep a simple list of completed areas so an interruption does not lead to accidental omissions.
After copying, compare file counts and sizes and inspect important samples. Remove source files only after successful verification and with backup arrangements established. Freeing space by deleting the only source during an unverified transfer removes exactly the fallback needed if something goes wrong.