From owner-freebsd-questions@FreeBSD.ORG Fri May 29 20:33:01 2015 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id BF390BBE for ; Fri, 29 May 2015 20:33:01 +0000 (UTC) (envelope-from mail@ozzmosis.com) Received: from homiemail-a83.g.dreamhost.com (sub5.mail.dreamhost.com [208.113.200.129]) by mx1.freebsd.org (Postfix) with ESMTP id A345E198C for ; Fri, 29 May 2015 20:33:00 +0000 (UTC) (envelope-from mail@ozzmosis.com) Received: from homiemail-a83.g.dreamhost.com (localhost [127.0.0.1]) by homiemail-a83.g.dreamhost.com (Postfix) with ESMTP id 683775E080; Fri, 29 May 2015 13:32:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=ozzmosis.com; h=date:from :to:cc:subject:message-id:references:mime-version:content-type: in-reply-to; s=ozzmosis.com; bh=Ma9/cmMY0LzzwUJfGk1mWClRBNc=; b= wHSE7hXcf3wMk0zUrKIa1jkxcFFOIqoX++cimhjo2N3Ve7NwTuwE6sGq94TR2U5H s/pTP843NzWsRx6iOseoKouvZVD1ANrCmPVtcr5fttLv7DBJf124mpd/4saTJN8C AgDgMoaBEohgDNC1rVHkPUhaRH510MAZJVHCjN7a04I= Received: from blizzard.ozzmosis.com (114-198-63-194.dyn.iinet.net.au [114.198.63.194]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: relay@ozzmosis.com) by homiemail-a83.g.dreamhost.com (Postfix) with ESMTPSA id 220AC5E07D; Fri, 29 May 2015 13:32:59 -0700 (PDT) Received: by blizzard.ozzmosis.com (Postfix, from userid 1001) id 3F48EC39; Sat, 30 May 2015 06:32:56 +1000 (AEST) Date: Sat, 30 May 2015 06:32:56 +1000 From: andrew clarke To: kpneal@pobox.com Cc: "freebsd-questions@freebsd.org" , Jaime Kikpole Subject: Re: ZFS in a VM? Message-ID: <20150529203256.GA57654@ozzmosis.com> References: <20150529092600.GA32731@ozzmosis.com> <20150529133653.GA94981@neutralgood.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150529133653.GA94981@neutralgood.org> User-Agent: Mutt/1.5.23 (2014-03-12) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 29 May 2015 20:33:01 -0000 On Fri 2015-05-29 09:36:53 UTC-0400, kpneal@pobox.com (kpneal@pobox.com) wrote: > > Keep in mind that large capacity ZFS datasets can require several GBs > > of memory to work well, particularly if you're using dedup, so you'll > > need to adjust your VM guest's memory appropriately. > > Be careful with dedup. The memory requirements are so large that with > large amounts of data is is easy to get into a situation that takes days > to recover from. > > When not using dedup: There are reports that ZFS can be used in as little > as 4GB of memory -- in the i386 FreeBSD at that! I've got a small setup > with 8GB of memory that works well for me, but I'm not using dedup until > I can put a lot more memory in this machine. I've used ZFS-on-root on amd64 with just 1.5 GB memory for a two-way 1 TB mirror without any dramas for over a year. I wasn't using dedup or snapshots, though, and I avoided running any userland software that ate lots of memory. This was also on bare metal, not a VM. It now has 4 GB, which is plenty.