On Wed, 29 Aug 2001 13:56:13 +1000, "Paul \(NCC/CS\)" wrote:
> I have several old small scsi disks. Small in capacity
> that is not in physical size:).  I am wondering if NetBSD
> has software for Volume management? ie I know on
> HP you can use the "volume manager" to make several
> small disks look like one big one. Quite useful. If we have
> software that does this what is it's name please? Or does
> it not exist? Or is there a technique to do the same job?

As a matter of fact, I just set this up myself.

Read the man page for "raidctl" and see if that answers your
questions? I pretty much used exactly the config file given in
the example.

The one thing I'm struggling with (that the man page didn't
address completely) is cylinder sizes and cylinders per group.
I think I messed up by leaving the cylinder size at the default
(instead of increasing it in disklabel), because the end result
was needing to increase the cylinders per group so that newfs
wouldn't choke on having too many cylinder groups.

It works the way it is, but I have one directory (=~ cylinder
group) that is so huge that it takes a long time to write
files there. I don't know exactly how to fix this, but I think
it has something to do with those parameters.

A few things I learned from doing this over the weekend:

	* Don't assume you'll only ever have one RAID array and
	  name the config file /etc/raid.conf... it has to be
	  /etc/raid0.conf, with the number, or else it won't be
	  found on bootup by the /etc/rc.d/raidframe script.

	* RAID "autoconfiguration" isn't worth it unless you really
	  want to have your root partition on the RAID array. The
	  aforementioned script will do a fine job.

	* The raidctl -i step takes a *long* time. You'd better
	  get your disklabels the way you want them before you do
	  it, or you'll waste a lot of time redoing the raidctl -i.

	* Instead of just having a backup root partition on each
	  disk, it might be safer to have a minimalistic /usr as well.

	* Don't swap on a RAID array -- it's overkill. The VM system
	  already does perfectly good interleaving. Allocate a bit
	  of every drive for swap on the top-level disklabel, not
	  the raid0 disklabel.

Post again if you have any specific questions after reading the
raidctl man page.

	~Ben