On Tue, 9 May 2006, Darren J Moffat wrote:
Paul van der Zwan wrote:
I just booted up Minix 3.1.1 today in Qemu and noticed to my surprise
that it has a disk nameing scheme similar to what Solaris uses.
It has c?d?p?s? note that both p (PC FDISK I assume) and s is used,
HP-UX uses the same scheme.
I think any system descending from the old SysV branch has the c?t?d?s?
naming convention.
I don't remember which version first used it but as far as I remember it
was already used in the mid 80's.
There is a difference though as far as I can tell. Sometimes on Solaris we
have p? for fdisk partitioning included and sometimes we don't; similarly we
sometimes don't have t? for target. Personally I'd prefer us to be
consistent always even if it leads to names like /dev/dsk/c0t0d0p0s0 if we
are talking about the first Solaris VTOC slice c0t0d0 for the whole disk
c0t0d0p0 for the whole Solaris VTOC.
I second the call for consistency, but think that this means dumping
partitions/slices from the actual device name. A disk is a disk - one unit
of storage. How it is subdivided and how/whether the subdivisions are made
available as device nodes should not be the worry of the disk driver, but
rather that of an independent layer. The way it is now may have a history
but that doesn't make it less confusing to me :(
The problem with the 'p' and 's' nodes is that they're _not_ used in
consistent fashions. You already noticed that Solaris/SPARC doesn't have
'p' nodes, and if e.g. you take a Solaris/SPARC disk and attach it to a
Solaris/x86 machine, you won't see it's 's' nodes either, and vice versa.
How clean is that ? Why on earth do we use different names for 'whole
disk' on SPARC/x86 ?
In short, why is it inevitabe to deal with disks _only_ if they have
labels ? Why no separate labeling layer ?
Then there is the issue of referencing FAT filesystems in size Windows
Extended partitions which would give rise to stuff like this
/dev/dsk/c0t0d0p0:1 at the moment :-) which is only really understood by
pcfs.
"understood" gives too much credit. PCFS acts on seeing this syntax, a
well-trained animal. That it actually understands what it does (and worse,
why it does so) is a bit far-fetched. And of course on SPARC, you'd rather
use /dev/dsk/c0t0d0s2:1 ... if you know ...
--
Darren J Moffat
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