From owner-freebsd-arm@freebsd.org Fri Feb 22 20:40:16 2019 Return-Path: Delivered-To: freebsd-arm@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 3FFB014FA738 for ; Fri, 22 Feb 2019 20:40:16 +0000 (UTC) (envelope-from sparvu@kronometrix.org) Received: from mail.kronometrix.org (mail.kronometrix.org [95.85.46.90]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mail.kronometrix.org", Issuer "mail.kronometrix.org" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id B67458794E for ; Fri, 22 Feb 2019 20:40:15 +0000 (UTC) (envelope-from sparvu@kronometrix.org) Received: from [192.168.1.191] (213-216-249-17.bb.dnainternet.fi [213.216.249.17]) (authenticated bits=0) by mail.kronometrix.org (8.15.2/8.15.2) with ESMTPSA id x1MKeC1O057053 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Fri, 22 Feb 2019 20:40:13 GMT (envelope-from sparvu@kronometrix.org) X-Authentication-Warning: mail.kronometrix.org: Host 213-216-249-17.bb.dnainternet.fi [213.216.249.17] claimed to be [192.168.1.191] From: Stefan Parvu Mime-Version: 1.0 (Mac OS X Mail 12.2 \(3445.102.3\)) Subject: Re: RBPI3B+ FreeBSD 12 ZFS Date: Fri, 22 Feb 2019 22:40:06 +0200 References: <5D976A97-9800-4A9F-A155-F3BD998AFB4C@kronometrix.org> <00523016-b7eb-8a61-8740-7463d793f969@denninger.net> <20190222185613.GA50742@server.rulingia.com> To: freebsd-arm@freebsd.org In-Reply-To: <20190222185613.GA50742@server.rulingia.com> Message-Id: <83C65D08-F8ED-4EB1-990C-E043D45E654D@kronometrix.org> X-Mailer: Apple Mail (2.3445.102.3) X-Rspamd-Queue-Id: B67458794E X-Spamd-Bar: ------ Authentication-Results: mx1.freebsd.org X-Spamd-Result: default: False [-6.97 / 15.00]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; REPLY(-4.00)[]; NEURAL_HAM_SHORT(-0.97)[-0.973,0] Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Porting FreeBSD to ARM processors." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 22 Feb 2019 20:40:16 -0000 Thanks all for comments. I need to dedicate time to play around with ZFS and RBPI3. Cheers Stefan Parvu sparvu@kronometrix.org > On 22 Feb 2019, at 20.56, Peter Jeremy wrote: > > On 2019-Feb-22 11:47:37 -0600, Karl Denninger wrote: >> Uh uh. Yes, a scrub (or just checksum check on the read) will catch the >> "aw crap!" situation where write amplification and read/rewrite hoses >> you during a power failure but there's nothing zfs can do to fix it >> since there's no second copy available. > > That's not completely true. By default ZFS stores 2 copies of most > metadata and can be configured to store up to 3 copies (on top of pool > redundancy) of all data (check the "copies" and "redundant_metadata" > properties of the filesystem). Obviously, if all the copies are on > one device, it won't help if the device bricks itself or all the > copies wind up on the corrupt sectors but it can help recovering from > a glitch that took out a page or two. (It would also be possible to > setup a ZFS mirror between a SDcard and a USB flash stick). > > -- > Peter Jeremy