I debated some of this with Bonwick (and Cantrill who really had no business being involved but he's pernicious that way) at the time. That blog post is, frankly, a bit misleading. The storage "stack" isn't really a stack. It's a DAG. Multiple kinds of devices, multiple filesystems plus raw block users (yes they still exist and sometimes even have reason to), multiple kinds of functionality in between. An LVM API allows some of this to have M users above and N providers below, for M+N total connections instead of M*N. To borrow Bonwick's own condescending turn of phrase, that's math. The "telescoping" he mentions works fine when your storage stack really is a stack, which might have made sense in a not-so-open Sun context, but in the broader world where multiple options are available at every level it's still bad engineering.

> ... but in the broader world where multiple options are available at every level it's still bad engineering.

When Sun added ZFS to Solaris, they did not get rid of UFS and/or SVM, nor prevent Veritas from being installed. When FreeBSD added ZFS, they did not get rid of UFS or GEOM either.

If an admin wanted or wants (or needs) to use the 'old' way of doing things they can.

Sorry, I'm pernicious in what way, exactly?

Heh. I was wondering if you were following (perhaps participating in) this thread. "Pernicious" was perhaps a meaner word than I meant. How about "ubiquitous"?