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Date:      Sat, 24 Jul 2010 09:01:13 -0400
From:      Dan Langille <dan@langille.org>
To:        Pawel Tyll <ptyll@nitronet.pl>
Cc:        Adam Vande More <amvandemore@gmail.com>, freebsd-stable@freebsd.org
Subject:   Re: Using GTP and glabel for ZFS arrays
Message-ID:  <4C4AE419.2020503@langille.org>
In-Reply-To: <136751861.20100724135630@nitronet.pl>
References:  <4C47B57F.5020309@langille.org> <4C48E695.6030602@langille.org>	<718046944.20100723032259@nitronet.pl>	<4C4A42D5.7080805@langille.org>	<AANLkTi=fMR1pQj11qCqMWwCM9nsovsm_PVh7%2BJeWF0ED@mail.gmail.com>	<AANLkTi=y%2BUJE9rgt-X3Wj6zHTCUfu67QnaDBzayb=a-5@mail.gmail.com> <136751861.20100724135630@nitronet.pl>

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On 7/24/2010 7:56 AM, Pawel Tyll wrote:
>> Easiest way to create sparse eg 20 GB assuming test.img doesn't exist
>> already

You trim posts too much... there is no way to compare without opening 
another email.

Adam wrote:

> truncate -s 20g test.img
> ls -sk test.img
> 1 test.img


> No no no. Easiest way to do what you want to do:
> mdconfig -a -t malloc -s 3t -u 0
> mdconfig -a -t malloc -s 3t -u 1

In what way is that easier?  Now I have /dev/md0 and /dev/md1 as opposed 
to two sparse files.

> Just make sure to offline and delete mds ASAP, unless you have 6TB of
> RAM waiting to be filled ;) - note that with RAIDZ2 you have no
> redundancy with two fake disks gone, and if going with RAIDZ1 this
> won't work at all. I can't figure out a safe way (data redundancy all
> the way) of doing things with only 2 free disks and 3.5TB data - third
> disk would make things easier, fourth would make them trivial; note
> that temporary disks 3 and 4 don't have to be 2TB, 1.5TB will do.

The lack of redundancy is noted and accepted.  Thanks.  :)

-- 
Dan Langille - http://langille.org/



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