You opened a file from the S3 drive and it appeared instantly. Where did it come from? The cache — the hidden local machinery that makes a cloud drive feel like a disk, and fills your C: drive if you ignore it.
Everything about a mounted S3 drive makes sense once you understand one thing: listing is cheap, touching is downloading. This guide explains the cache honestly — what sits in S3, what quietly lands on your own disk, and why your edits reach the cloud later than you think.
How a mounted S3 drive actually works. Only the files you touch take space on your own disk.
When you open S: and see a thousand files, it feels like they are on your PC. They are not. TntDrive asks S3 for the list and shows it. A file only travels to your computer when you open it, and when it arrives it is stored in a local cache folder on your own drive so that opening it again is fast.
This is why the mounted drive does not eat disk space on day one — and why it slowly starts to, the more you use it.
Open a document from the S3 drive, and you are editing the cached local copy. When you save and close the program, TntDrive uploads the whole updated file back to the bucket. Two honest consequences follow:
Months later your system drive is full and the S3 drive gets blamed for the wrong reason — it is the cache, full of every big file you ever opened. Keep it under control:
On a train with no signal, your S3 drive will show you whatever happens to already be in the cache — and nothing else. Uploads will wait or fail. So plan honestly: copy anything you truly need offline onto a real local folder before you travel, and treat the cache as a speed helper, not as an offline copy of your bucket.
Every click shown live — installing TntDrive, adding the S3 account and mapping the drive in Windows.
▶️ Watch Full VideoNo — as long as the files finished uploading. The cache holds local working copies of files whose originals live in the bucket. Clearing it only means the next open downloads the file again. The one exception: edits that were still waiting to upload. Let pending uploads finish before clearing.
Yes. TntDrive lets you choose the cache location in its settings. Moving it to a larger D: drive is one of the smartest early settings if your Windows drive is a small SSD.
Yes, through the cache — roughly the total size of the files you have opened or edited recently. A bucket of 500 GB does not need 500 GB locally, but a week of opening big videos can easily park tens of GB in the cache until you clear it.