Just a datapoint. Switching a Dell poweredge 350 (entry level
	celeron 850) running RAIDFRAME on two 111GB disks from both
	disks on the same channel to individual channels changed the
	bonnie++ numbers as below:

Version  1.01       ------Sequential Output------ --Sequential Input- --Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  /sec %CP
same-channel   300M  9239  31 10083  18  4019   7  7402  29  8841   8  89.2   3
separate-chan  300M  9441  31 10214  18  5370  10  8271  34 10943  11 140.0   4

                    ------Sequential Create------ --------Random Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP
same-channel     16   484  85 +++++ +++  5155  52   286  49   324  49   797  49
separate-chan    16   433  76 +++++ +++  4760  49   289  49   331  50   811  50


On Wed, 7 Aug 2002, Curt Sampson wrote:

> On Tue, 6 Aug 2002, Wojciech Puchar wrote:
>
> > but using master/slave config is bad idea and will slow down everything.
>
> This is not necessarially true. Testing with modern 7200 RPM IBM IDE
> drives on a UDMA-100 controller, I found that sequential reads and
> writes were basically unaffected. I.e., with one drive I got about 30
> MB/sec; with two drives on the same controller I got about 30 MB/sec
> from each, when being read or written simultaneously.
>
> What *was* affected was the number of disk transactions I could get
> per second; with one disk or two, I could do no more than about 90
> transactions per second. So if you do a lot of small reads and writes,
> this might be a problem; if you're not sustaining a high transaction
> rate, it may make no difference.
>
> cjs
>

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