From owner-freebsd-arch@freebsd.org Thu Jan 23 02:07:12 2020 Return-Path: Delivered-To: freebsd-arch@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 42DC4227FAE for ; Thu, 23 Jan 2020 02:07:12 +0000 (UTC) (envelope-from mike@karels.net) Received: from mail.karels.net (mail.karels.net [216.160.39.52]) by mx1.freebsd.org (Postfix) with ESMTP id 4835Hz0JBTz3Nqb; Thu, 23 Jan 2020 02:07:10 +0000 (UTC) (envelope-from mike@karels.net) Received: from mail.karels.net (localhost [127.0.0.1]) by mail.karels.net (8.15.2/8.15.2) with ESMTP id 00N274xO042659; Wed, 22 Jan 2020 20:07:04 -0600 (CST) (envelope-from mike@karels.net) Message-Id: <202001230207.00N274xO042659@mail.karels.net> To: Ben Woods cc: Conrad Meyer , freebsd-arch@freebsd.org, Ed Maste , Philip Paeps From: Mike Karels Reply-to: mike@karels.net Subject: Minimum memory for ZFS (was Re: svn commit: r356758 - in head/usr.sbin/bsdinstall: . scripts) In-reply-to: Your message of Thu, 23 Jan 2020 08:06:59 +0800. MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <42657.1579745224.1@mail.karels.net> Content-Transfer-Encoding: quoted-printable Date: Wed, 22 Jan 2020 20:07:04 -0600 X-Rspamd-Queue-Id: 4835Hz0JBTz3Nqb X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of mike@karels.net designates 216.160.39.52 as permitted sender) smtp.mailfrom=mike@karels.net X-Spamd-Result: default: False [-4.42 / 15.00]; ARC_NA(0.00)[]; HAS_REPLYTO(0.00)[mike@karels.net]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip4:216.160.39.52]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[karels.net]; REPLYTO_ADDR_EQ_FROM(0.00)[]; RCPT_COUNT_FIVE(0.00)[5]; TO_MATCH_ENVRCPT_SOME(0.00)[]; IP_SCORE(-2.22)[ip: (-7.28), ipnet: 216.160.0.0/15(-3.67), asn: 209(-0.11), country: US(-0.05)]; FREEMAIL_TO(0.00)[gmail.com]; RCVD_NO_TLS_LAST(0.10)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:209, ipnet:216.160.0.0/15, country:US]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Jan 2020 02:07:12 -0000 I took the liberty of changing the subject line to make it stand out a bit more. Ben wrote: > On Sat, 18 Jan 2020 at 09:16, Mike Karels wrote: > > > On Fri, 17 Jan 2020 at 08:21, Ben Woods wrote: > > > > > > Perhaps we could simply include a message on that bsdinstall > > partitioning > > > > mode selection screen that UFS is recommended on systems with < 4 = Gb > > RAM? > > > > > > > > > I have uploaded a diff for this here: https://reviews.freebsd.org/D2= 3224 > > > > > Please let me know your thoughts (comments in the phabricator review > > would > > > be best). > > > > I think this needs more discussion, preferably on this list. I am not > > convinced that systems with as little as 4 GB should use ZFS. Convent= ional > > wisdom on the FreeNAS mailing list says that 8 GB is required for ZFS, > > and FreeNAS no longer includes UFS as an option. Conrad suggested a > > cutoff of 16 GB; I am happier with 16 GB than 4 GB as a cutoff. Also, > > there was mention of auto-tuning for smaller systems; I don't think th= at > > has materialized yet. I'm not sure how plausible that is without know= ing > > the workload. I use ZFS on a workstation/server with 64 GB that runs = 4 > > bhyve guests that do things like buildworld. ZFS wants 63 GB for arc_= max; > > needless to say, I have a tunable set to a much lower value. If tunin= g > > is required, it is unclear that ZFS is a good default. > > > > Mike > > > Hi everyone, > Before I commit phabricator review D23224, is there any final comments? > Particularly on these 2 lines of help-text: > msg_partitioning_zfs_help=3D"ZFS is recommended if you have at least 4GB= RAM" > msg_partitioning_ufs_help=3D"UFS is recommended if you have less than 4G= B of > RAM" > There is some disagree about what these 2 recommendations should be. > 4GB was recommended by: imp, emaste, philip, eugen, dteske > 8GB was recommended by: mike > 16GB was recommended by: cem > The 4GB limit seems to have the best consensus, however there was some > debate about whether ZFS is recommended on a system with 4GB, or only > systems with MORE THAN 4GB. I don't remember what everyone else wrote, but IIRC, Devin said that if you use ZFS with 4 GB, you will soon end up with a dozen tunables set. That doesn't sound like a recommendation for 4 GB. > As for the ZFS auto-tuning, I see that as being a separate discussion > (which could ultimately change this recommendation, but shouldn't preven= t > us from committing this help text now). Agreed, but the lack of tuning should factor into the current recommendati= on. Mike > Regards, > Ben