Re: RAM disk

["Nino on NetBSD 4.0" <nbsdold%gmx.net@localhost>]

Dear All,

Actually, I have no NetBSD in front of me now,
so I am sorry not to be able to tell you what
exactly I am doing or what the response was.

What I want is indeed a memory DISK, not just
a memory FILESYSTEM, so Ignatios' description
hits exactly what I want.

What I did - I somehow created an md0 with
mdconfig, but could not mount it - so I assumed
it needs a filesystem, and thus ran newfs on it.
But all the time I just got some error message
along the lines of "device busy". So how do I
correctly set up a RAM DISK with a filesystem
on it? Could you kindly show me which sequence
of commands is necessary? Thank you in advance.

I have to say, the md0c of the manpage did not
exist, there were md0a and md0d if I correctly
remember - and both failed for me.

(What I want is a bit hard to say, by the way -
I am trying to write down some quick notes for
"the occasional desktop user" with a certain but
small UNIX experience. You will get them soon
I hope.)

Kind regards,

Nino

-------- Original-Nachricht --------
> Datum: Wed, 11 Feb 2009 12:29:34 +0100
> Von: Ignatios Souvatzis <ignatios%cs.uni-bonn.de@localhost>
> An: 
> CC: netbsd-users%NetBSD.org@localhost
> Betreff: Re: RAM disk

> On Wed, Feb 11, 2009 at 11:41:13AM +0100, Nino on NetBSD 4.0 wrote:
> 
> > I tried to configure a RAM-disk on NetBSD 4.0.
> > ... mount_mfs ... mdconfig ...
> 
> Different uses.
> 
> Actually, very different uses.
> 
> With mount_mfs and the more modern mount_tmpfs, you create and mount
> an *empty* temporary *filesystem* in virtual memory -  that is, it's
> written to your swap device on memory shortage.
> 
> mdconfig creates an instance of a memory *disk* accessed through the
> device "/dev/mdN" or "/dev/rmdN" for some integer N. The alternative
> is to have a memory disk inside of the kernel that is used (you fill
> it with mdsetimage). You still have to create a filesystem on it and
> mount that. Most often, it is used with an embedded filesystem image
> that contains the installation scripts or for similar purposes.
> 
> Regards,
>       -is

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