the 'why' of pseudofs

[Bill Hacker]

Folks,

Google was no help, and I have only the last 54,000 or so of the 
DragonFlyBSD newsgroup messages to hand on on the PowerBook, wherein a 
message-body search on pfs, PFS, pseudofs turned up only about 240 or so 
messages, or Mark One eyeball processing..

That now done, I find:

Several of these cover conception, gestation, birth, and education  - 
the 'what' or 'how' of pseudofs / PFS, so to speak.

ONE of which lists the pro /con vs PFS_NOT. And that one not really 
hard-edged.

NONE of which tell me with any degree of absolute-ish-ness, if you will..

. .. that one cannot, or even 'should not' run a HAMMER fs *without* PFS 
mounts.

. .. or nullfs mounts.

or even .... without softlinks.  Persih the htought. Or the confusion...

At all.

EG: 'none of the above'.

Mind - I see the rationale - even necessity - for their use in more than 
a few circumstances.

But I cannot seem to find the prohibitions against their 'non-use'.

What do you suppose breaks if I do not apply these in an initial setup, 
but rather leave them until specific needs arise, such as volume 
expansion, export, or mirroring?

I have in mind small drive(s) for /, /usr, /var/, /tmp, /home
- perhaps not even hammerfs, those. Nothing there that was ever overly 
hard to backup, restore, of JF replace. My mailstore, for exampel, has 
never lived in any of those. Nor web pages. Nor Databases.

It is on separate, much larger, drive(s) for /data, /mail, /web, /pub 
and such - where 'mission critical' clients live and play.

UFS(1), / FFS(1)  - not UFS2/FFS2 has made for less hassle when hardware 
goes pear-shaped or OS migration is afoot.

Enter (BF)HAMMER

But what concept am I missing here? Nice-to-have? Or absolute necessity?

Regards,

Bill