Subject: Re: ccd and cylinder locations
To: gabriel rosenkoetter <>
From: Greywolf <>
List: current-users
Date: 01/18/2002 10:13:11
On Fri, 18 Jan 2002, gabriel rosenkoetter wrote:

# On Fri, Jan 18, 2002 at 08:30:49AM -0800, Greywolf wrote:
# > No, you do not need to newfs the partitions separately.  You simply
# > concatenate them, write a disklabel to them and then newfs the
# > aggregate.
# So the answer to the question I actually asked (do I lose what's on
# the disk now) is, in fact, yes?

Unfortunately, this is the case.

# And this also means that we don't support later adding additional
# disks to a given ccd?

Unfortunately, this, too, is the case.

ccd is a cheap and dirty (no offense intended to its implementors/
designers) way to slap a few partitions together to make a bigger
disk.  It could certainly benefit from extensibility.  The trick,
as I understood it to be, is that as you change the "geometry" of
the disk, the result of the spare-superblock calculation also changes,
so unless you commit a list of superblocks somewhere, or unless you
find someplace to stash the old ones, and preserve the data blocks that
inhabit the place where superblocks are going to live, you're going
to lose something.

The reorganization of such an operation is not, from my extremely
limited point of view, exactly what I would term as "trivial",
but as I'm not a fs hacker, what do I know...?  Anyone have any
insight as to how Solaris, HP/UX, AIX or IRIX manage to do this?

NetBSD: The Power of Code.