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Date:      Fri, 18 May 2001 10:39:33 +1000 (EST)
From:      Stephen Cimarelli <stephen@clari.net.au>
To:        Marcus Reid <marcus@blazingdot.com>
Cc:        Gabriel Ambuehl <gabriel_ambuehl@buz.ch>, Jonathan Fortin <jfortin@akalink.com>, questions@FreeBSD.ORG, Greg Lehey <grog@lemis.com>
Subject:   Re: Raid (BEST PERFORMANCE)
Message-ID:  <XFMail.010518103933.stephen@clari.net.au>
In-Reply-To: <20010517011226.A4473@blazingdot.com>

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Raid levels has seen by Mylex


Level 0+1  Combines Daid 0 striping and Raid1 mirroring

Level 10  Combines  raid0 striping and Raid 1 mirroring spanned across multiple
drive groups

level 30  Combines Raid 0 and raid 3 across multiple drive groups

Level 50  Combines Raid 0 and raid 5 across multiple drive groups


is there some offical body that decided on what level 10,30,50 are, or do
companys make up there own


On 17-May-01 Marcus Reid wrote:
> On Thu, May 17, 2001 at 04:50:26PM +0930, Greg Lehey wrote:
>> On Wednesday, 16 May 2001 at 22:07:48 -0700, Marcus Reid wrote:
>> > On Tue, May 08, 2001 at 06:22:26PM +0200, Gabriel Ambuehl wrote:
>> >>
>> >> Hello Jonathan,
>> >> Monday, May 07, 2001, 7:08:48 PM, you wrote:
>> >>> Best Performance Raid is a raid 0+1 setup.
>> >>> For example, you got 4 20gb harddrives.
>> >>> You create 2 strips of 2hds eachs, and you mirror them.
>> >>> It will have redundancy and the speed will be as fast as a normal
>> >> disk. It's
>> >>> basically a Raid-1 setup with 2 hard drives per strip instead of one
>> >> to
>> >>> counter write performance hits.
>> >> Some vendors like to call this RAID 10 (hmm. 1+0=10? only if those are
>> >> strings...).
>> >
>> > If I'm not mistaken, there's a difference between 0+1 and 10: one is
>> > striped and then mirrored, the other is mirrored and then striped. It's
>> > supposed to have some bearing on performance, 0+1 being the faster one.
>> 
>> I've heard people make this kind of claim.  I can't understand what
>> the difference is supposed to be.  Can you justify it?
> 
> It's something that I read on the qmail list; people were talking about
> the best RAID scheme to use for a very high-volume mail server. I don't
> have anything to offer from personal experience. I'm assembling a new mail
> machine very soon and have to select which level of RAID to use, so I'd
> be interested to hear if there's any truth behind it.
> 
> Marcus
> 
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E-Mail: Stephen Cimarelli <stephen@clari.net.au>
Date: 18-May-01
Time: 10:26:23
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