Have the device names for hard discs been changed?

[Gavin Atkinson]

On Sun, 29 Jan 2006, Christian Baer wrote:

> When I installed new drives (ad0, which is the boot drive and ad8 which
> is the new one), I created a new slice (dd-mode[1]) and new partition(s)
> without any problems. I did notice that the letter for a single
> partition changed from 'e' to 'd'. So a drive containing only a single
> file system now is /dev/adxs1d[2].

I'm not sure it was ever 'e'.  I'm also confused by what you mean by 
"dd-mode" - the footnote suggests you're talking about "dangerously 
dedicated" mode, but the fact you created a slice and have "s1" in all of 
your device names suggests that you are in fact not running in dangerously 
dedicated mode.

> After that I started sysinstall and created a new slice and a new
> partition which sysinstall called /dev/ad6s1d - which I expected. But
> after creating the partition, the mount failed, because "no such file or
> directory". And sure enough, ad6s1d did not exist in /dev/:
>
>  jon# ls -l /dev/ad6*
>  crw-r-----  1 root  operator    0,  76 Jan 22 15:23 /dev/ad6
>  crw-r-----  1 root  operator    0,  93 Jan 22 15:00 /dev/ad6c
>  crw-r-----  1 root  operator    0,  96 Jan 22 15:00 /dev/ad6cs1
>  crw-r-----  1 root  operator    0,  92 Jan 22 15:00 /dev/ad6s1
>  crw-r-----  1 root  operator    0,  94 Jan 22 15:00 /dev/ad6s1c

What's the output of:
  - fdisk /dev/ad6
  - fdisk /dev/ad6s1
  - disklabel /dev/ad6
  - disklabel /dev/ad6c
  - disklabel /dev/ad6s1
?

I wonder if somehow GEOM is getting confused and seeing it both as a 
dd-mode disk, and as a normal disk?

> These devices look a bit like those of a drive with a "true"
> partition-table (so Wintendo can read it). I can't really check that now
> because I have no computer with such an installation. However, even if
> this *were* so, I have checked and rechecked, the drive is definately
> dangerously dedicated - or at least, it should be. None of the other
> drives show these devices:
>
>  crw-r-----  1 root  operator    0,  73 Jan 22 16:20 /dev/ad0
>  crw-r-----  1 root  operator    0,  79 Jan 22 16:20 /dev/ad0s1
>  crw-r-----  1 root  operator    0, 100 Jan 22 16:20 /dev/ad0s1a
>  crw-r-----  1 root  operator    0, 101 Jan 22 16:20 /dev/ad0s1b
>  crw-r-----  1 root  operator    0, 102 Jan 22 16:20 /dev/ad0s1c
>  crw-r-----  1 root  operator    0, 103 Jan 22 16:20 /dev/ad0s1d
>  crw-r-----  1 root  operator    0, 104 Jan 22 16:20 /dev/ad0s1e
>  crw-r-----  1 root  operator    0, 105 Jan 22 16:20 /dev/ad0s1f
>  crw-r-----  1 root  operator    0, 106 Jan 22 16:20 /dev/ad0s1g
>  crw-r-----  1 root  operator    0,  78 Jan 22 16:20 /dev/ad12
>  crw-r-----  1 root  operator    0,  97 Jan 22 16:20 /dev/ad12s1
>  crw-r-----  1 root  operator    0, 121 Jan 22 16:20 /dev/ad12s1c
>  crw-r-----  1 root  operator    0, 122 Jan 22 16:20 /dev/ad12s1e
>  crw-r-----  1 root  operator    0,  74 Jan 22 16:20 /dev/ad2
>  crw-r-----  1 root  operator    0,  87 Jan 22 16:20 /dev/ad2s1
>  crw-r-----  1 root  operator    0, 109 Jan 22 16:20 /dev/ad2s1c
>  crw-r-----  1 root  operator    0, 110 Jan 22 16:20 /dev/ad2s1e
>  crw-r-----  1 root  operator    0,  75 Jan 22 16:20 /dev/ad4
>  crw-r-----  1 root  operator    0,  90 Jan 22 16:20 /dev/ad4s1
>  crw-r-----  1 root  operator    0, 113 Jan 22 16:20 /dev/ad4s1c
>  crw-r-----  1 root  operator    0, 114 Jan 22 16:20 /dev/ad4s1d
>  crw-r-----  1 root  operator    0,  77 Jan 22 16:20 /dev/ad8
>  crw-r-----  1 root  operator    0,  94 Jan 22 16:20 /dev/ad8s1
>  crw-r-----  1 root  operator    0, 117 Jan 22 16:20 /dev/ad8s1c
>  crw-r-----  1 root  operator    0, 118 Jan 22 16:20 /dev/ad8s1d

... none of these other disks look like they are being used in dd-mode.

> [2] Is there some text out there explaining these last letters? What are
>    the first three letters (a-c) reserved for? The handbook seems to be
>    a little out of date.

Traditionally, 'a' is root, 'b' is swap, and 'c' is the whole disk.  As 
far as I know, they no longer have any special/implied meaning in FreeBSD 
(other than 'a' on the boot disk), but the tradition of reserving a-c has 
been retained for compatibility with other OS's.

Gavin