Note: I’m not asking how to use a different filesystem. I’m asking for the reasoning behind the choice of ext4.
Ubuntu (21.10) uses ext4 by default. But, there are a great many other filesystems that have great features. ZFS, for example, can stripe disks (see RAID-Z). There are other good ones, for example XFS has great performance for a very large number of files.
So, what is the rationale for picking EXT4 as the default?
>Solution :
Ubuntu did not "pick" ext4. Debian did.
Mark Shuttleworth’s original vision was to create a not-quite-fork of Debian that could sign contracts, collect revenue, and hire engineers. A corollary to that vision of Debian-for-enterprise was that Ubuntu had to hew very close to stock Debian.
It still does. That’s why Ubuntu uses Debian sources, apt, NetworkManager, systemd, …and ext4… among many other Debian-made decisions.
The Ubuntu Foundations Team does have the authority to strike a different path, and on occasion it has done so. But, for most issues, the Ubuntu Foundations Team has agreed with the Debian consensus.
Ubuntu and Debian do run happily on many different filesystems, and users can install Debian or Ubuntu on those filesystems fairly easily. Debian’s default, however, remains ext4. And nobody has yet presented the Ubuntu Foundations Team a compelling reason for Ubuntu to differ.