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Date:      Wed, 23 Jan 2013 22:22:48 +0100
From:      Michel Talon <talon@lpthe.jussieu.fr>
To:        Mark Felder <feld@feld.me>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: ZFS regimen: scrub, scrub, scrub and scrub again.
Message-ID:  <101D6382-BF57-43EB-A5FA-A63D4062F5FD@lpthe.jussieu.fr>

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On Wed, 23 Jan 2013 14:26:43 -0600, Chris Rees <utisoft@gmail.com> wrote:

>
> So we have to take your word for it?
> Provide a link if you're going to make assertions, or they're no more  
> than
> your own opinion.

I've heard this same thing -- every vdev == 1 drive in performance. I've  
never seen any proof/papers on it though.


first google answer from request "raids performance"
https://blogs.oracle.com/roch/entry/when_to_and_not_to

Effectively,  as  a first approximation,  an  N-disk RAID-Z group will
behave as   a single   device in  terms  of  delivered    random input
IOPS. Thus  a 10-disk group of devices  each capable of 200-IOPS, will
globally act as a 200-IOPS capable RAID-Z group.  This is the price to
pay to achieve proper data  protection without  the 2X block  overhead
associated with mirroring.



--

Michel Talon
talon@lpthe.jussieu.fr






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