Date: Sun, 19 Dec 2021 23:59:42 +0000 From: spellberg_robert <emailrob@risebroadband.net> To: freebsd-questions@freebsd.org Subject: ada[0-5] versus ahcich[0-5] on 11.4_amd64 Message-ID: <1ae74128-36a6-816b-e2c3-1c38c85903dd@risebroadband.net> In-Reply-To: <7e5dc966-0660-849d-f534-acbd90d3966f@risebroadband.net> References: <7e5dc966-0660-849d-f534-acbd90d3966f@risebroadband.net>
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2021_dec_19_sun
howdy , folks ---
it has been a_while , so , i hope that all of you_and_yours are well ;
we are doing just fine .
in this post , all platforms are fbsd_amd64 ,
on intel "skylake" "i3/5/7" cpus
[ coming_soon , "rocket_lake" , thanks to "avx_512" ] ,
with "z170" chip_sets , on "atx"_format moboes ,
in "mid_tower"_sized cases , except as noted .
context
-------
one specific thing which i liked about fbsd ,
when i discovered it about 20 years ago
[ 3.5.1 , 4.2 ; after using 4bsd on vaxen in grad_school ] ,
compared to the ms_platform , which it replaced , was that
hard_disk_drives were identified by the mobo_socket ,
to which they were attached ,
rather than by some probe_order
[ anyone remember "drive_letter shifting" ? ] .
as i recall , this characteristic remained through my 9.3 boxen .
on my 10.3 boxen , "/dev/ada[0-5]" entries appeared ,
along with "/dev/ad[0-5]" sym_links to these entries .
of these two styles , both were valid in "/etc/fstab" ;
so , i continued to use the "/dev/ad[0-5]" style .
very recently , i have been converting to 11.4 , for regular use ,
and , soon , i will build a 12.2 box , for testing .
i choose to rely upon the last minor_number , for each major_number ,
until the next major acquires its last minor [ 12.4 ? ] .
exceptions to this policy are rare
[ simply , i never "got_around_to" 10.4 ] .
on my initial 11.4 box ,
i observed that the "/dev/ad[0-5]" style no_longer appeared .
this did_not concern me , until
i installed , later , an additional hdd .
-- sha_ZAM !!! -- [ thank you , "captain marvel" ] .
fbsd has , now , that ms_platform "feature" ,
which is known , affectionately , as "drive_letter shifting" .
i was perplexed ; for a_while , i ruminated .
then , i examined "/var/run/dmesg.boot" ,
in which i found these selected entries [ there are 6 sockets ] :
cd0 at ahcich0 ... [ on mobo_sata_socket_1 ] ,
ada0 at ahcich1 ... [ on mobo_sata_socket_2 ] ,
ada1 at ahcich2 ... [ on mobo_sata_socket_3 ] ,
ada2 at ahcich4 ... [ on mobo_sata_socket_5 ] ,
ada3 at ahcich5 ... [ on mobo_sata_socket_6 ] .
the partition "/dev/ada0p3" is mounted at "/" .
for cable_management reasons , i prefer to use the nearest socket .
research
--------
it is remarkable how_much one can learn from the fbsd_handbook ,
the "man"_pages and "that inter_web thing"
[ this is why i have not posted a question , in quite some time ] .
so , i began to read .
alas , i have found nothing , so_far ,
which addresses , directly , this concept .
i --have-- found some_thing about "hdd_labelling" ;
how_ever , none of my --numerous-- drives are "labelled" ,
including those from foreign platforms ;
thus , this does not help .
i have enough trouble inventing unique identifiers in my code ;
they change over time , almost in_variably .
also , i found some_thing about
combining the "ata"_driver with the "scsi"_driver
[ aha ! ; a potential explanation ] .
i have never used scsi drives , for three reasons :
a] i do not run a "server_farm" , requiring higher reliability ;
b] they are more expensive [ i maintain many back_ups ] and
c] their identification depends upon their location along a cable
[ like "pata" ] .
question
--------
from the boot_messages [ above ] ,
i know that the mobo_socket is known , at some point , during boot .
is there a way to identify a sata_hdd , by its mobo_socket ,
in a manner which will satisfy "/etc/fstab" ?
in advance , regarding this matter , i thank every_one for
their suggestions , complaints and great_thoughts and i remain
very sincerely yours ,
rob
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