Carrierwave uploader consuming memroy

I am using Carrierwave uploader V0.10.0 for my rails project (on RHEL) to upload 310 MB of zip file to server. While file is being transferred, I could see the server's available memory is decreasing. After file gets download and when call come to the controller to save the uploaded file, I could see the deduction of 3 times (of zip file, say 930 MB) size of memory from available file system space. I am not able to figure out why its happening.

Any help is great.