Do I need to format both SSD partitions when switching from Windows to Linux?

You'll only need to format the partition where you plan to install Linux. The other partition can remain untouched, which means your files should remain intact unless you actively modify them. However, using it's not a completely reliable backup method; just be cautious with file operations on that partition through Linux as it could potentially lead to data issues later on. Linux can easily read NTFS partitions, but I'd also suggest switching off fast startup in Windows if you still have it installed, as it can cause issues accessing those partitions later. If you want the best compatibility across both systems, consider formatting the shared partition as exFAT instead of NTFS.

If you're worried about losing files or data corruption, the safest option is to back up everything externally. You can always disconnect that drive before installing Linux to avoid any potential issues during the installation process. Just keep in mind that once you switch to Linux, it handles file formats quite well, so you shouldn’t have too many worries about accessing documents or files across the partitions.

Linux does a good job reading NTFS and FAT32 partitions used by Windows. You shouldn't run into too many problems accessing your files once you install Linux, just make sure the files are in supported formats.

To share files easily between Windows and Linux, formatting the shared partition as FAT32 can work well if you're just dealing with documents or PDFs. It’s not the best option for large files, but it’s a solid choice for general documents.