Exercise 2: Which Architecture Makes Swapping RAID Vendors Easier — Possible Solution
====================================================================

Answer: The traditional layered architecture makes this easier.

Explanation:

Per the chapter, the traditional stack's own "real benefit is
composability: any single layer can be swapped without touching the
others -- hardware RAID in place of mdadm, XFS in place of ext4." In
a traditional stack, RAID is a genuinely separate layer sitting below
LVM and the filesystem, communicating with the layers above it only
through the standard block-device interface. Because LVM and the
filesystem only ever see "a block device" regardless of which specific
RAID implementation is producing it underneath, replacing one
hardware RAID controller's array with a different vendor's hardware
RAID controller's array changes nothing that LVM or the filesystem
depend on -- as long as the new array presents itself as a block
device of the right size, the layers above are unaffected.

The integrated approach doesn't offer this same swap. Per the chapter,
"swapping ZFS's own RAID-Z for a different vendor's RAID
implementation isn't really an option the way swapping mdadm for
hardware RAID is in the traditional stack" -- because ZFS's redundancy
mechanism (RAID-Z) is built directly into the filesystem/pool system
itself, rather than being a separate, swappable layer underneath it,
there is no clean boundary at which a different vendor's RAID
implementation could be substituted in without effectively replacing
the entire storage system, not just one layer of it.

For a team specifically prioritizing the future flexibility to change
RAID hardware vendors without disrupting the filesystem/volume layout
above it, the traditional stack's explicit layer boundaries are the
architecture built for exactly that kind of substitution.

WHY THIS WORKS AS AN ANSWER
------------------------------
This identifies the specific chapter passage each architecture's own
swappability claim comes from, and explains WHY the traditional
stack's layer boundary (a standard block-device interface) is what
makes the swap safe, while explaining why the integrated approach has
no equivalent boundary to swap at.