Tape Device file differences...

[Andreas Kohn]

On Thu, 2003-10-16 at 22:12, Marco Greene (Home) wrote:
> ..I am a little confused about tape devices in FreeBSD.
> 
> Under the /dev directory...I have the following tape devices:
> # ls *sa*
> ersa0           esa0.1          nrsa0.3         rsa0.0          sa0.1
> ersa0.0         esa0.2          nsa0            rsa0.1          sa0.2
> ersa0.1         esa0.3          nsa0.0          rsa0.2          sa0.3
> ersa0.2         nrsa0           nsa0.1          rsa0.3          sa0.ctl
> ersa0.3         nrsa0.0         nsa0.2          rsa0.ctl
> esa0            nrsa0.1         nsa0.3          sa0
> esa0.0          nrsa0.2         rsa0            sa0.0
> 
> I have figured out most of it by searching on the net...but any
> clarification or pointers to documentation would be helpful.
> 
> This is what I have figured out so far (feel free to correct me if I am
> wrong).
> -e[r]sa0 = Eject
> -n[r]sa0 = No Rewind
> -[r]sa0 = Rewind
> -The .ctl file should be used with the "mt" command.
> 
> 
> 
> This is what I still need explained:
> -The difference between the /dev/*rsa0 devices and /dev/?sa0 devices?  i.e.
> What is the "r" for?
The r stands for "raw" access (vs. "block" access without r) IIRC.
The sa(4) manpage has more information about the different modes of the
tape, which are coded into the first and second bit of the minor number
(see ls -l /dev/*sa*)

> -What is the .0, .1, .2 and .3?
I think those refer to different units. /dev/sa0 is a symlink to
/dev/sa0.0 on my machine.

> 
> Thanks,
> Marco
> 
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-- 
Andreas Kohn <andreas.kohn at gmx.net>
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