From owner-freebsd-fs@freebsd.org Fri Jul 1 12:17:10 2016 Return-Path: Delivered-To: freebsd-fs@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 70DC7B86A14 for ; Fri, 1 Jul 2016 12:17:10 +0000 (UTC) (envelope-from 000.fbsd@quip.cz) Received: from elsa.codelab.cz (elsa.codelab.cz [94.124.105.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 318712679 for ; Fri, 1 Jul 2016 12:17:09 +0000 (UTC) (envelope-from 000.fbsd@quip.cz) Received: from elsa.codelab.cz (localhost [127.0.0.1]) by elsa.codelab.cz (Postfix) with ESMTP id 40C4B28450; Fri, 1 Jul 2016 14:17:07 +0200 (CEST) Received: from illbsd.quip.test (ip-86-49-16-209.net.upcbroadband.cz [86.49.16.209]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by elsa.codelab.cz (Postfix) with ESMTPSA id 7CBB028416; Fri, 1 Jul 2016 14:17:06 +0200 (CEST) Message-ID: <57765F42.4090904@quip.cz> Date: Fri, 01 Jul 2016 14:17:06 +0200 From: Miroslav Lachman <000.fbsd@quip.cz> User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:35.0) Gecko/20100101 Firefox/35.0 SeaMonkey/2.32 MIME-Version: 1.0 To: Ben RUBSON , freebsd-fs@freebsd.org Subject: Re: HAST + ZFS + NFS + CARP References: <71b8da1e-acb2-9d4e-5d11-20695aa5274a@internetx.com> <20160630153747.GB5695@mordor.lan> <63C07474-BDD5-42AA-BF4A-85A0E04D3CC2@gmail.com> <20160630163541.GC5695@mordor.lan> <50BF1AEF-3ECC-4C30-B8E1-678E02735BB5@gmail.com> <20160701084717.GE5695@mordor.lan> <47c7e1a5-6ae8-689c-9c2d-bb92f659ea43@internetx.com> <20160701101524.GF5695@mordor.lan> <20160701105735.GG5695@mordor.lan> <5776569B.3050504@quip.cz> <5F99508D-7532-468A-9121-7A76957A72DB@gmail.com> In-Reply-To: <5F99508D-7532-468A-9121-7A76957A72DB@gmail.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 Jul 2016 12:17:10 -0000 Ben RUBSON wrote on 07/01/2016 13:58: >> With ZFS send & receive you will lose some writes but the chance you will corrupt both pools are much lower than in the first case and the setup is much simpler and runtime error proof. > > Only some ? > Depending on the write throughput, won't you loose a lot of data on the target/slave ? > How do you make ZFS send/receive quite realtime ? > while [ 1 ] do ; snapshot ; send/receive ; delete old snapshots ; done ? It depends on throughput and how often do you send. But you need to compare it to the HAST / iSCSI scenario. Even with this setup ZFS don't write to disk immediately but in batch delayed according to some sysctl settings and you will lose this amount of data in all cases + data on clients which cannot write and must restart their NFS sessions (again this apply to HAST / iSCSI scenario) If you will ZFS send often, you can lose about 2 or 4 times more. It depends on you if it is too much or not. Miroslav Lachman