[ fbsd_quest ] file_caching and hd caches

[spellberg_robert]

howdy, y'all ---

so, i was looking over the offerings of the on_line retailing "usual suspects",
   when i got to thinking:

   q:  to what extent does freebsd cache recently_used hard_drive files ?

   q:  under freebsd, to what extent are
         hard_drive internal_caches and their sizes [ e. g., 2mb, 8mb, 16mb ]
         important ?



i am not so much looking for a history_ and theory_of_operation as
   i am looking for a "yes/no" to the question:

   q:  should i pay up for hd_cache, if the other hd parameters are the same ?



something else that i just thought up while typing this:

   q:  are hd internal_caches non_volatile ?

id est,

   q:  do the cache contents survive a power_cycle ?



[ some supplementary "fyi"s:

     yes, i am aware that
       hd access_times are a relative "eternity" to a chip_set's hd_port.

     i am not thinking about ram_size and swap_size and "thrashing";
       all of my boxen have plenty of ram.

     i know i have to read it in the first time.
     rather, i am thinking about opening and reading
       some file that i recently wrote and closed.
]



in advance, i thank you.
please cc.

rob



ps --- remember, slavery sucks; so, have a happy pesach.