Nginx problem with upload files

hi, dear all:

I am a newbie to nginx. Firstly thanks for your attentions.
I have one problem about nginx:
I install nginx on machine A, and install other tools on machine B &
C…
When uploading(PUT) one file to B or C, I found that when uploading,
all the data flow are uploaded to nginx machine A at first, then the
files
are sent to machine B or C. I hope the uploading files are sent to B or
C
directly, not passing from A. is nginx able to do this? If yes, how to
config that.
I am wondering that if there are lots of clients doing I/O operations
together, the nginx A
should be the I/O bottleneck.

Many thanks.

BRs,
feng