Subject: Re: VPS mailing list, BSD interest?
To: James R Grinter <>
From: Darren Reed <>
List: tech-kern
Date: 10/02/1996 22:18:58
In some mail from James R Grinter, sie said:
> [large cc lists trimmed, i think everyone must be on one of the two
> lists]
> On Wed 2 Oct, 1996, matthew green <> wrote:
> >i also like the model of ODS (as under solaris 2):
> >	- a metadevice acts like a normal disk partition
> >	- a metadevice can be composed of any number of real partitions
> >	  or metadevices, either concatenated or striped, or mirrored.
> Each logical volume has a name which is used when referring to the
> logical volume device (/dev/{r,}dsk/xlv/volumename), and consists
> of log, data, and real-time data sub-volumes. Each sub-volume
> consists of a number of volume elements (each being a disk partition),
> which can be concatenated or striped together.  A sub-volume can
> contain up to 4 plexes (SGI's term for mirrors), each being up to
> 128 volume elements.

Hmmm, having used LVM, seen ccd docs, to me, it should be something
like this:

|                  |  LVM    |     |
|       disks      +---+-----+ CCD |
|                      |           |
|    hd* sd* xd*       +-----------+
|                                  |

That is, a file system can exist on a normal disk, a meta disk or a logical
disk.  An LV can be an arbitary size, with an entire `disk' allocated to the
VG (Volume group), there are no predined LV boundaries, except what is and
isn't allocated (currently) to a LV.
A CCD is less flexible and is either a collection of disks or disk partitions
and is fixed in size.

How the device names are organised should be immaterial, IMHO.
(Well, except if you have FreeBSD 2.2 :-)