Comment by throw0101a

> However it happened, modularity is still a good thing.

It may be a good thing, and it may not. Linux has a bajillion file systems, some more useful than others, and that is unique in some ways.

Solaris and other enterprise-y Unixes at the time only had one. Even the BSDs generally only have a few that they run on instead of ext2/3/4, XFS, ReiserFS (remember when that was going to take over?), btrfs, bcachefs, etc, etc, etc.

At most, a company may have purchased a license for Veritas:

* https://en.wikipedia.org/wiki/Veritas_Storage_Foundation

By rolling everything together, you get ACID writes, atomic space-efficient low-overhead snapshots, storage pools, etc. All this just be removing one layer of indirection and doing some telescoping:

* https://blogs.oracle.com/bonwick/rampant-layering-violation

It's not "modularity bad", but that to achieve the same result someone would have had to write/expand a layer-to-layer API to achieve the same results, and no one did. Also, as a first-order estimate of complexity: how many lines of code (LoC) are there in mdraid/LVM/ext4 versus ZFS (or UFS+SVM on Solaris).