Subject: Using CCD driver to improve disk I/O.....
To: None <netbsd-help@netbsd.org>
From: Sung N. Cho <sucho2@vt.edu>
List: netbsd-help
Date: 03/02/2002 13:44:09
Hi,

I heard that by using ccd (concatenated/striped disk devices), one can 
improve the disk I/O.  I read the manual (ccd) but it's more of dictionary of 
what ccd is and does.  It fails to describe how to set it up.  Anybody knows 
how to set this up?  Here's my disklabel info:

# /dev/rwd0d:
type: unknown
disk: mydisk
label:
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 15
sectors/cylinder: 945
cylinders: 10068
total sectors: 9514260
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # microseconds
track-to-track seek: 0  # microseconds
drivedata: 0

8 partitions:
#        size    offset     fstype  [fsize bsize cpg/sgs]
 a:    204120    725760     4.2BSD   1024  8192    80   # (Cyl.  768 - 983)
 b:    524475    929880       swap                      # (Cyl.  984 - 1538)
 c:   8788500    725760     unused      0     0         # (Cyl.  768 - 10067)
 d:   9514260         0     unused      0     0         # (Cyl.    0 - 10067)
 e:    103005   1454355     4.2BSD   1024  8192    96   # (Cyl. 1539 - 1647)
 f:   6624450   1557360     4.2BSD   1024  8192    80   # (Cyl. 1648 - 8657)
 g:   1332450   8181810     4.2BSD   1024  8192     0   # (Cyl. 8658 - 10067)
 h:    725697        63      MSDOS                      # (Cyl.    0*- 767)


What do I need to modify for this to work?
Also, in my kernel config file, I have:
pseudo-device	ccd		4	# concatenated/striped disk devices

Do I need to increase the number 4 to 5 as in # of partitions or is this 
corresponding to 4 physical disks?

Thank you.


Sung N. Cho