I want to learn more about file systems from the practical point of view so I know what to expect, how to approach them and what experience positive or negative you had / have.
I found this wikipedia's comparison but I want your hands-on views.
For now my mental list is
NTFS - for some reason TVs on USB love these and also Windows + Linux can read and write this
Ext4 - solid fs with journaling but Linux specific
Btrfs - some modern fs with snapshot capability, Linux specific
xfs - servers really like these as they are performant, Linux specific
FAT32 - limited but recognizable everywhere
exFAT - like FAT32 but less recognizable and less limited
Ext4 for system disks because it's default in OS installers and it works well. I typically use it on top of LVMRAID (LVM-managed mdraid) for redundancy and expansion flexibility.
ZFS for storage because it's got data integrity verification, trivial setup, flexible redundancy topologies, free snapshots, blazing fast replication, easy expansion, incredible flexibility in separating data and performance tuning within the same filesystem. I'd be looking into setting up ZFS on root for my next machine. Among other things that would enable trivial and blazing fast backup of the system while it's running - as simple as syncoid -r rpool backup-server:machine4-rpool.
I'd be looking into setting up ZFS on root for my next machine
I too was on the path of adventure once but then the kernel module hasn't been built after the upgrade. Also btrfs offers some nice features for root especially that zfs doesn't have.
You can boot straight into snapshot, may be useful if an update went wrong or you don't like new kde.
You can change drives and raid configuration online. For example I bought a laptop that had windows preinstalled, so I used the second half of the disk space for linux, then I figured I don't need windows so I formatted windows partition to btrfs, added it as a new device, moved all the data there, deleted the old linux partition and extended the new one to the whole drive, all that easy and without reboot.
Oh nice. I think that all of those are possible with ZFS too. Although I'm pretty sure that the snapshot-boot is done outside of ZFS itself. As in, there's something else that takes the snapshots and makes them available to the bootloader. I think zsys used to do that in the experimental ZFS-on-root support that shipped in Ubuntu 20.04. I recall having a snapshot appear before every update and those snapshots were selectable from GRUB.