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Date: Fri, 07 Jun 2013 19:18:45 +0300
From: Volodymyr Kostyrko <c.kworr@gmail.com>
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To: Quartz <quartz@sneakertech.com>, 
 FreeBSD questions <freebsd-questions@freebsd.org>
Subject: Re: ZFS: raid VS copies=n
References: <51B201D4.3000705@sneakertech.com>
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07.06.2013 18:52, Quartz:
> Question:
>
> How does the ZFS option 'copies=n' and raid relate to and interact with
> each other? specifically recovery in the event of a failure. For
> example, is having three disks in a raid-1 configuration with copies=1
> effectively the same as having three disks in a raid-0 with copies=3?
> Are the copies distributed uniformly across all drives in the pool, or
> concentrated, or what? What happens with configs like a raid-z2 with
> copies=2? Which / how many disks can you lose?
>
> (I'm aware that like a lot of other ZFS options copies=n doesn't have to
> be global to the entire pool / directory structure, but for the sake of
> simplicity let's assume it is in this case).

copies=n tries to allocate blocks on different disks but doesn't 
guarantee this nor that any single disk can be used to retrieve data.

-- 
Sphinx of black quartz, judge my vow.