Subject: Re: ccd disklabel: What's the geometry
To: None <netbsd-help@NetBSD.ORG>
From: Andreas Brusinsky <brusinsk@ibdr.inf.tu-dresden.de>
List: netbsd-help
Date: 11/25/1996 13:55:49
> activity, you should probably use (MAXBSIZE / DEV_BSIZE) for the
> interleave.
Where can one lookup those variables (e.g. MAXBSIZE or DEV_BSIZE)
that appear quite ofte in the man pages.
Certainly I configurred the somehow the harddisks but there never
appeared those variable names. So if I'm not sure what the actual 
value of DEV_BSIZE is where do I have to look for???

> So, a nice ccd would look sort of like this:
> 
> component	scsibus		target
> 0		0		0
> 1		1		0
> 2		2		0
> 3		3		0
> 4		0		1
> 5		1		1
> 6		2		1
> 7		3		1
> 
> ...etc.  You get the idea :-)
I don't. What is target 0 and what is target 1 when I just have one ccd?
What is the component?

>  If your interleave were (16k / DEV_BSIZE),
so what is 16k/DEV_BSIZE? Is 16k=16384
 or 16000? Is DEV_BSIZE=bytes/sector or bsize or fsize?

> an optimal 64k transfer would happen concurrently across 4 SCSI busses.
But if someone has three or two scsi drives what is then optimal?
And SCSI busses is probably not the same as SCSI drives.
So if one connects three SCSI dirves in a hp external drive box, does he
have then 3 scsi buses or just one?


	Please forgive a rude sound of this.
	I just would like to know a little more about ccd's.

I also believe that it is better to put a new filesystem onto
ccd drive with rather the added parameters of the real drives, instead
of letting 'newfs' use the parameters of the calculated disklabel of the ccd.


	Bye Andreas