I have about 1 million small files, that take up about 20 GB. I need to upload them to a host that only has 23 GB free space. I would prefer compressing the files locally to increase the transmission speed (would it work btw?), but I don't think I will be have enough free space to unpack the file (there is no need to keep the archive). Is there any compression format that would allow decompressing the file with that little free space?