From owner-freebsd-hackers@freebsd.org Wed Dec 23 17:07:57 2015 Return-Path: Delivered-To: freebsd-hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 8340CA4F7A9 for ; Wed, 23 Dec 2015 17:07:57 +0000 (UTC) (envelope-from fjwcash@gmail.com) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 6A62414A7 for ; Wed, 23 Dec 2015 17:07:57 +0000 (UTC) (envelope-from fjwcash@gmail.com) Received: by mailman.ysv.freebsd.org (Postfix) id 690B8A4F7A6; Wed, 23 Dec 2015 17:07:57 +0000 (UTC) Delivered-To: hackers@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 68A16A4F7A5 for ; Wed, 23 Dec 2015 17:07:57 +0000 (UTC) (envelope-from fjwcash@gmail.com) Received: from mail-ob0-x232.google.com (mail-ob0-x232.google.com [IPv6:2607:f8b0:4003:c01::232]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 38C2714A6 for ; Wed, 23 Dec 2015 17:07:57 +0000 (UTC) (envelope-from fjwcash@gmail.com) Received: by mail-ob0-x232.google.com with SMTP id ba1so77245278obb.3 for ; Wed, 23 Dec 2015 09:07:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=fHYOTJGP1lzvojfPPgcDGCsIUVjkZFhpwjZLkL0oNQE=; b=YJklQizbZlkYQ1sMdS1F8JzODX/WajHxW3fa+HRMmR0fPMGwH7gQU3hiXQo3JIGgyi mf4yymqk6UhlYCWr4Qx4UWm9iUyUqQtbm1I0f85FwA9uEIeHL56hcnbxUWigOwV0ZbZY KAg8qY7aCLISah41nXdbsWnVmL2aeOxCr6HURYC9EMDRsYaJ/HACyr86RJpKRqxKFe8l PkOojQRtWhY3oTnqjg4gxAOvED7kIcapbDmMvTecocO/Nh3P7RYhSm5Ug06h4BjnwP9w xeNR7bn/RHlIuwm9wAFKZIBrMzrUl8An3p5Et5U+YjulZvUspDSQuP3FH1gkyr8cRfBv wwpA== MIME-Version: 1.0 X-Received: by 10.182.24.9 with SMTP id q9mr15220245obf.73.1450890476599; Wed, 23 Dec 2015 09:07:56 -0800 (PST) Received: by 10.76.172.195 with HTTP; Wed, 23 Dec 2015 09:07:56 -0800 (PST) In-Reply-To: References: Date: Wed, 23 Dec 2015 09:07:56 -0800 Message-ID: Subject: Re: The minimum amount of memory needed to use ZFS. From: Freddie Cash To: Stephen Hocking Cc: "hackers@freebsd.org" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 23 Dec 2015 17:07:57 -0000 On Wed, Dec 23, 2015 at 2:43 AM, Stephen Hocking wrote: > Inspired by this article: > > http://arstechnica.com/information-technology/2015/12/rsync-net-zfs-repli= cation-to-the-cloud-is-finally-here-and-its-fast/ > > I am wondering about changing my offsite back strategy, which currently i= s > made up of a Raspberry Pi with an external 3TB drive sitting at my > brother's house, with periodic manual rsyncs. I'd like to change that to > doing zfs replications. > > I want to use some of my ARM based hardware as the target for the ZFS > replication, owing to its low power usage. I have a few Cubiboxes floatin= g > around with around 2G of RAM, and a RPI2 or a Banana Pi with 1G. It'd hav= e > a UFS root on the SD card, and ZFS on the external drive. > > Any ideas? > =E2=80=8BMy lowest powered / lowest performing ZFS-based system was an Inte= l Pentium4 3.0 GHz single-core setup with 2 GB of RAM, running 32-bit FreeBSD. Used a 2 GB USB stick for the / filesystem (including /usr), and 4x 120 GB IDE drives in a raidz1. Back in the late FreeBSD 7 / early FreeBSD 8 days. It took a lot of tinkering with =E2=80=8B =E2=80=8Bthe kernel config, loader.conf, and sysctl.conf to make it stable.= But it eventually worked quite nicely. Used it for several years. Even migrated it over to 4x=E2=80=8B 160 GB SATA1 drives in raidz1, then to 500 GB SATA2 = drives in two mirror vdevs, then to ZFS-on-root. The last migration changed the motherboard for one that supports an AMD Phenom-II quad-core at 2.something GHz with 8 GB of RAM. And the to 4x 1 TB drives. Over the holidays, I'll be adding another mirror vdev (total of 3, using 6 drives) and another 8 GB of RAM. ZFS runs better with more RAM; and it requires less manual tuning with more RAM. But it's definitely possible to run it with less RAM. You just need to be willing to spend time tuning, tweaking, and testing. I wouldn't want to run it on an RPi, though. The CPU is just too weak to compute the checksums (unless you go for a weak/fast algorithm) and to do any compression. I've heard good things from people using Intel Atom CPUs, though. --=20 Freddie Cash fjwcash@gmail.com