From owner-freebsd-questions@FreeBSD.ORG  Thu Nov 24 19:19:21 2011
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id C4E60106566C
	for <freebsd-questions@freebsd.org>;
	Thu, 24 Nov 2011 19:19:21 +0000 (UTC)
	(envelope-from apseudoutopia@gmail.com)
Received: from mail-bw0-f54.google.com (mail-bw0-f54.google.com
	[209.85.214.54])
	by mx1.freebsd.org (Postfix) with ESMTP id 563AC8FC0C
	for <freebsd-questions@freebsd.org>;
	Thu, 24 Nov 2011 19:19:20 +0000 (UTC)
Received: by bkbzs8 with SMTP id zs8so4299747bkb.13
	for <freebsd-questions@freebsd.org>;
	Thu, 24 Nov 2011 11:19:20 -0800 (PST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma;
	h=mime-version:in-reply-to:references:date:message-id:subject:from:to
	:cc:content-type:content-transfer-encoding;
	bh=Wlk7bizE1o+3HmXeHo7w4c7pprVRXrhmOdUgSOA1DRQ=;
	b=VzR1lTGS1vG4CD57T9/GOol5HyRGJZ8k4XeFw1eWUbEXh9FiZ1XADzrHNmjReQo4xJ
	38dkzZSOJYZAl/bVbTlho3fOaz0WGwa19cfR2ZcZlHl68RNAwZRNoofLOOTAex4kdmiO
	EbLjCJdXz5h1308bRP9AcYDoimLJlD0QQr9XA=
MIME-Version: 1.0
Received: by 10.205.120.145 with SMTP id fy17mr30950631bkc.124.1322162360125; 
	Thu, 24 Nov 2011 11:19:20 -0800 (PST)
Received: by 10.204.133.215 with HTTP; Thu, 24 Nov 2011 11:19:19 -0800 (PST)
In-Reply-To: <4ECB580E.20203@infracaninophile.co.uk>
References: <CAKOHg=PEqeMPN_2dfQ+4msi1j7CMUu=iO+pSuezRoa_CELzQtw@mail.gmail.com>
	<88f3d8e819b3420f8e61723bee90ba5e.squirrel@www.magehandbook.com>
	<CAKOHg=N4yt0vdac8aZMUTK+8EnoSwxhK+yWmy7MsOXvKrWEmyw@mail.gmail.com>
	<4ECB580E.20203@infracaninophile.co.uk>
Date: Thu, 24 Nov 2011 14:19:19 -0500
Message-ID: <CAKOHg=PWcpqHdyvaS+oRwghA5m-A-rMxF-wqw3ZAPERzmO+pRw@mail.gmail.com>
From: APseudoUtopia <apseudoutopia@gmail.com>
To: Matthew Seaman <m.seaman@infracaninophile.co.uk>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
Cc: freebsd-questions@freebsd.org
Subject: Re: Setting up ZFS - Filesystem Properties and Installing on Root
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 24 Nov 2011 19:19:21 -0000

On Tue, Nov 22, 2011 at 3:06 AM, Matthew Seaman
<m.seaman@infracaninophile.co.uk> wrote:
> On 22/11/2011 02:09, APseudoUtopia wrote:
>> Another quick question about swap: If I have 4 drives, with 512MB
>> swap, the system uses all 4 swap partitions, correct? So it's not like
>> it'd be going to waste? I'd have a total of 2 GB swap?
>
> Well, yes. =C2=A0If you just declare those raw partitions to be swap area=
s,
> that will be the case. =C2=A0However, doing this is asking for trouble: y=
ou
> subvert any resilience features obtained by using ZFS with raidz1. =C2=A0=
If
> any one of the drives fails, your swap area will break and your system
> will probably crash.
>
> Better to set up two pairs of gmirrors for swap -- the procedure is
> described here: http://wiki.freebsd.org/RootOnZFS/GPTZFSBoot/Mirror
> in section3 "Finish Install." =C2=A0This will effectively give you a raid=
10
> for your swap, with a total size of 1GB.
>

I'm not sure I understand this. How would that negatively affect the
raidz1? The swap isn't in the zpool. I understand the system may crash
if the OS was using the swap space and the drive failed. But would you
not be able to reboot into a degraded zpool state and still have a
usable system?