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Date: Mon, 19 Sep 2016 06:51:13 +0200
From: Polytropon <freebsd@edvax.de>
To: Olivier <Olivier.Nicole@cs.ait.ac.th>
Cc: questions@freebsd.org
Subject: Re: /dev/ad vs. /dev/ada
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On Mon, 19 Sep 2016 11:27:07 +0700, Olivier wrote:
> I am wondering what is the difference between driver /dev/ad and
> /dev/ada.
> 
> I have been using /dev/ad for years, but now I notice there is also the
> drivers /dev/ada. ad is not in the man anymore, but still working like
> it used to.
> 
> So, what is the differece.

The "ad" device driver is for (parallel) ATA drives, "ada" is
"advanced da", with "da" being the driver for generic SCSI
direct access devices which cover SATA devices when they
are accessed using the AHCI controller interface.

Similarly to abolishing the "acd" device driver (ATAPI CDs)
which are now covered with the "cd" driver (SCSI CD). The
method "SCSI oder ATA", formerly performed by the ATAPICAM
facility, is now the default for storage access.

See "man ad", "man da", "man ahci", and "man ada" for details.


-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...