Need advice - easiest way to log and read/process data on device

I’m looking for some advice on the following situation:

I’m planning on logging some data that my device captures over a 8-12h period, roughly logging every 2-5 minutes somewhere between 2-4 double variables per log. Each day will be a new file.

I want to process this data on-board doing some basic calcs, nothing to intensive, but I need to be able to read and process one day’s file at a time.

I was hoping someone with some experience could suggest the nicest/easiest way to do the above, ideally with some libraries to do the heavy lifting.

The only thing that comes to mind for me is to use the Cesanta Frozen library to log in JSON format and read back the vars from file. I’ve got no idea how large/memory intensive this will be…

Thanks

Just found the docs on jstore, looks like it might make my life a little easier. I haven’t had much luck doing the writing/reading on my own.

https://mongoose-os.com/docs/mongoose-os/api/misc/jstore.md

Just trying out jstore and came across this comment while looking for examples.

Anyone know why @cpq would have said not to use jstore anymore?