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Date:      Sun, 15 Dec 2002 17:11:58 -0800
From:      "Jin Guojun [NCS]" <j_guojun@lbl.gov>
To:        Hari Bhaskaran <subscr@spider.netmails.net>
Cc:        freebsd-hardware@FreeBSD.ORG
Subject:   Re: Optimal conf for two HDDs + 1 CD on 2 UDMA/100 channels
Message-ID:  <3DFD285E.96FE73AD@lbl.gov>
References:  <20021215184343.A64802@spider.netmails.net>

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There are a couple of separated issues in answering your question:

(1) Not all IDE controllers are really works in stripping well.
(2) Does an inactive IDE device will affect an active IDE device?

You seem concerning the second issue in your email. It is usually not
the problem.
However, the first issue may be a problem, and it depends on what type of
IDE controller you have.

For example: 
AMD MPX IDE controller has two real IDE buses, which give you over
190 MBps aggregated throughput. So, stripping will help.
Intel PCI chip sets seem not have two really separated IDE buses. So, it
does not matter how you connect your drives, you will not get aggregated
throughput near 100 MBps. So, do whatever it is convenient for you, 
it will not make different.
VIA/ALi/NVIDIA/SiS chip sets all have different features.

So, you need to test your IDE controllers to decide how you connect
your drives. Normally, what you proposed is a better way.

	-Jin

Hari Bhaskaran wrote:
> 
> Hi,
> 
> I plan to use vinumfs on FreeBSD 4.7 using two IDE harddisks 120G each.
> Motherboard has two UDMA/100 IDE slots.
> 
> If I didn't have the CD, I would expect it will be better to put both
> HDDs on different cables since they wouldn't compete for the channel
> that way. But then the CD would have to be at least a slave on one of
> the cables. Would it degrade the performance of the HDD on the same
> cable?. The CD drive is Mitsumi SR242S1 -- an I am not sure if it is
> slow or fast. I would use the CD only rarely (probably only during
> initial install). The HDD doc says it is OK to put a CD on the
> same cable so long as the HDD is the master. Would that take care of
> any performance issues?
> 
> Is any one configuration better suited for FreeBSD or vinumfs for that
> matter. Any help is greatly appreciated
> 
> --
> Hari Bhaskaran
> 
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