When I try to upload a folder
with many sub folders (about 7gb)
unfortunately the s3cmd memory consumption is pretty big. I suggest
to split the upload into smaller chunks. Instead of uploading your
floder1 all at once run a sync for folder1/subfldr1, then for
folder1/subfldr2, etc. It doesn't matter how much space the files in
each subfolder occupy, only the number of files in each is relevant.
So split the upload evenly across chunks of directories with roughly
the same number of files if possible.