# CAMS zip files compressed mode is not enabled **URL:** \ **Category:** CAMS - Datasets and Usage\ **Tags:** api\ **Created:** [27 September 2024 11:29 UTC](https://forum.ecmwf.int/t/cams-zip-files-compressed-mode-is-not-enabled/6427 "2024-09-27T11:29:08Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Cyril\_Joly](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/c/6a8cbe/32.png) [@Cyril\_Joly](https://forum.ecmwf.int/u/Cyril_Joly)\ **Post date:** [27 September 2024 11:29 UTC](https://forum.ecmwf.int/t/cams-zip-files-compressed-mode-is-not-enabled/6427/1 "2024-09-27T11:29:08Z")
I have noticed that when downloading CAMS products, they are provided as ZIP files. I understand that this format offers advantages, especially when a user queries multiple NetCDF files simultaneously. However, it seems that no compression is enabled: for a single file, the size of the ZIP file is identical to that of the extracted NetCDF file. _This raises two questions:_ 1. Why is compression not enabled for the ZIP files? 2. Why isn’t internal zlib compression used within the NetCDF files themselves? I suspect the answer might be related to the computational load on the servers, but it seems unfortunate that such large, uncompressed files are being queried. ---
**Author:** ![Luke\_Jones](https://forum.ecmwf.int/letter_avatar_proxy/v4/letter/l/e0b2c6/32.png) [@Luke\_Jones](https://forum.ecmwf.int/u/Luke_Jones)\ **Post date:** [27 September 2024 15:03 UTC](https://forum.ecmwf.int/t/cams-zip-files-compressed-mode-is-not-enabled/6427/2 "2024-09-27T15:03:58Z")
Hi Cyril. I completely agree. Unfortunately it’s a little bit complicated because some files benefit hugely from compression while others don’t at all, and compressing needlessly wastes time and resources as you say. It’s on our to-do list to implement a better approach to compression and I’m hoping we’ll achieve that in the coming weeks. Luke.