[pso] FreeBSD disk raw I/O

[Alexandru Goia]

Buna seara,

Iata link-uri despre devices raw in FreeBSD :

0.1. FreeBSD Architecture Handbook --
http://www.freebsd.org/doc/en/books/arch-handbook/index.html
0.2. Block Devices (Are Gone) --
http://www.freebsd.org/doc/en/books/arch-handbook/driverbasics-block.html

1. FreeBSD defineste un device caracter ca un device pe care poti citi/scrie
direct (dintr-un proces).
 -- http://www.freebsd.org/doc/en/books/arch-handbook/driverbasics-char.html

Sa inteleg ca in terminologia FreeBSD un device "caracter" == device "raw"
in terminologia UNIX ?

2. FreeBSD renunta la device-uri block.
 --
http://www.freebsd.org/doc/en/books/arch-handbook/driverbasics-block.html

Sa inteleg ca imediat deasupra disk devices-urilor raw se poate aseza un
filesystem, fara a avea intre ele un layer
de block-devices ? Zic bine "block-devices", sau trebuie inlocuit cu
termenul "buffer cache" (asa cum e in cartea lui
Bach, "The Design of the UNIX O.S."), ori cu termenul "block I/O layer" (asa
cum e intitulat un capitol din cartea lui
Love "Lnx.Ker.Devel.") ?

A face raw I/O inseamna precis a face acces direct la un device (terminal,
disk, retea), fara buffering la vreun nivel ?


Doresc sa inteleg atat in termeni generali, cat si in detaliu (cat pot eu,
la acest moment) aceste chestiuni, pe Linux
si FreeBSD.


Va multumesc,
Alexandru
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