Date: Wed, 2 Oct 1996 22:18:58 +1000 (EST) From: Darren Reed <avalon@coombs.anu.edu.au> To: jrg@demon.net (James R Grinter) Cc: mrg@eterna.com.au, hackers@freebsd.org, tech-kern@netbsd.org Subject: Re: VPS mailing list, BSD interest? Message-ID: <199610021219.FAA02036@freefall.freebsd.org> In-Reply-To: <E0v8PF4-0005Nt-00@chacal.noc.demon.net> from "James R Grinter" at Oct 2, 96 12:13:29 pm
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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 <mrg@eterna.com.au> 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:
+----------------------------------+
| FFS/UFS/NTFS/LFS/VXFS/EXT2/... |
+------------------+---------+-----+
| | 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 :-)
Darren
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