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Date:      Mon, 06 Mar 2000 02:52:36 +0000
From:      Ralph Seguin <rpseguin@yahoo.com>
To:        freebsd-questions@FreeBSD.ORG
Subject:   CCD striped disks are no faster than conventional
Message-ID:  <38C31D74.4BB1D272@yahoo.com>

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Hi.
Any idea on why my striped ccd partition is no faster than any other
paritition?
I would expect to see much faster reads and writes.
I've tried a variety of interleaves between 16 and 512 and the speed is
more or less constant.
I have two IDE drives, each on a different IDE channel.
Kernel is configured ok, I've already built the filesystem and
everything.

Setup:  FreeBSD 3.3-RELEASE
Pentium III 500, 256M RAM, 13GB + 9GB

13GB disk:
nutmeg# disklabel -r /dev/wd0
# /dev/wd0:
type: ESDI
disk: wd0s1
label:
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 255
sectors/cylinder: 16065
cylinders: 1662
sectors/unit: 26712000
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
drivedata: 0

8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  a:    81920        0    4.2BSD     1024  8192    16   # (Cyl.    0 -
5*)
  b:  1058592    81920      swap                        # (Cyl.    5*-
70*)
  c: 26712000        0    unused        0     0         # (Cyl.    0 -
1662*)
  e:   614400  1140512    4.2BSD     1024  8192    16   # (Cyl.   70*-
109*)
  f:  5210368  1754912    4.2BSD     1024  8192    16   # (Cyl.  109*-
433*)
  g: 19746720  6965280    4.2BSD     1024  8192    16   # (Cyl.  433*-
1662*)


nutmeg# disklabel -r /dev/wd2
# /dev/wd2:
type: ESDI
disk: wd1s1
label:
flags:
bytes/sector: 512
sectors/track: 63
tracks/cylinder: 255
sectors/cylinder: 16065
cylinders: 1229
sectors/unit: 19746720
rpm: 3600
interleave: 1
trackskew: 0
cylinderskew: 0
headswitch: 0           # milliseconds
track-to-track seek: 0  # milliseconds
drivedata: 0

8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  c: 19746720        0    unused        0     0         # (Cyl.    0 -
1229*)
  e: 19746720        0    4.2BSD     1024  8192    16   # (Cyl.    0 -
1229*)


nutmeg# cat /etc/ccd.conf
ccd0      64      none    /dev/wd0s1g /dev/wd1s1e


Thanks.
-Ralph







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