Re: Manual creation of a vnd image - newfs freezes

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Wed, Jan 24, 2007 at 07:56:50PM +1100, Sarton O'Brien wrote:
> On Wednesday 24 January 2007 06:22, Manuel Bouyer wrote:
> > vnd0a is the block device; it goes though the buffer cache. rvnd0a is
> > the character device, it talks directly to the driver. I guess using
> > vnd0a you fill up the buffer cache quickly, and the system crawls because
> > it has no free memory.
> 
> I guess the obvious question then is, does this indicate a problem with my 
> system? And is there any way to diagnose the problem ...

No, it's not a problem with your system, it's know behavior with
vnd.

> 
> It seems strange to me that newfs would cause this under a dom0.
> 
> Sorry to stray but I tried looking through the NetBSD guide and searched a 
> bit 
> but I haven't found any documentation:
> 
> >From memory, the character device under FreeBSD would be, for example, wd0c. 
> Under NetBSD what is wd0c? I understand wd0d to be the whole disk (buffered) 
> and now rwd0d to be the whole disk as a character device but the purpose of 
> wd0c (or rwd0c) under NetBSD has eluded me.

wd0c is not 'character' device, it's the 'raw' device (without any offset
translation from the disklabel). it'a also the device that can always be
openned, even for e.g. a removable media without media inserted.

On NetBSD it's wd0d on i386 and xen, and wd0c everywhere else (for historical
reasons)

> 
> Actually ... just looking at disklabel ... is wd0c the whole disk minus the 
> mbr?

It is if you installed NetBSD on the whole disk. It's the NetBSD partition
of the disk in the mbr parititon table.

-- 
Manuel Bouyer, LIP6, Universite Paris VI.           
Manuel.Bouyer%lip6.fr@localhost
     NetBSD: 26 ans d'experience feront toujours la difference
--