Is PostgreSQL database write to cooked files?

Since PostgreSQL database is write to an UNIX filesystem
in $PGDATA directory It not likes other database such as Sybase,
Informix write to a raw disk.

I am wonder are those files under $PGDATA/data/base/dbname/
directory cooked files?
Can I copy or ftp them to other machine running PostgreSQL without
export/import (pg_dump)?

BTW, Does PostgreSQL support mirror database?
Because I want to have two machine running PostgreSQL.
One use for operational, one use for backup (I mean mirror everything).

Thank you very much!

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Why we want to teach our babies to talk and walk,
then later we tell them "sit down!", "be quiet!" ?

Democracy is not a better way for a solution,
it is just another way to spread the blames.

--Raymond