From owner-freebsd-fs@FreeBSD.ORG Mon Jun 22 13:17:38 2015 Return-Path: Delivered-To: freebsd-fs@nevdull.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 312E1804 for ; Mon, 22 Jun 2015 13:17:38 +0000 (UTC) (envelope-from bfriesen@simple.dallas.tx.us) Received: from blade.simplesystems.org (blade.simplesystems.org [65.66.246.74]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id ECB842B1 for ; Mon, 22 Jun 2015 13:17:37 +0000 (UTC) (envelope-from bfriesen@simple.dallas.tx.us) Received: from freddy.simplesystems.org (freddy.simplesystems.org [65.66.246.65]) by blade.simplesystems.org (8.14.4+Sun/8.14.4) with ESMTP id t5MDHZlJ004931; Mon, 22 Jun 2015 08:17:36 -0500 (CDT) Date: Mon, 22 Jun 2015 08:17:35 -0500 (CDT) From: Bob Friesenhahn X-X-Sender: bfriesen@freddy.simplesystems.org To: Quartz cc: FreeBSD FS Subject: Re: ZFS raid write performance? In-Reply-To: <5587C3FF.9070407@sneakertech.com> Message-ID: References: <5587C3FF.9070407@sneakertech.com> User-Agent: Alpine 2.01 (GSO 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.2 (blade.simplesystems.org [65.66.246.90]); Mon, 22 Jun 2015 08:17:36 -0500 (CDT) X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 Jun 2015 13:17:38 -0000 On Mon, 22 Jun 2015, Quartz wrote: > What's sequential write performance like these days for ZFS raidzX? Someone > suggested to me that I set up a single not-raid disk to act as a fast > 'landing pad' for receiving files, then move them to the pool later in the > background. Is that actually necessary? (Assume generic sata drives, > 250mb-4gb sized files, and transfers are across a LAN using single unbonded > GigE). The primary determinant of write performance is if the writes are synchronous or not, With synchronous writes, the data is comitted to non-volatile storage before responding to the requestor. With asyncronous writes, the data only needs to be written into RAM before responding to the requestor. Writes over NFS 3 are synchronous. Writes over CIFS/Samba are likely not. For good performance with synchronous writes, some sort of non-volatile write cache (e.g. dedicated zfs intent log "slog", controller NVRAM) is advised. Use multiple sets of mirrors for maximum write performance with multiple clients. Even 10 years old hardware should be able to keep up with gigabit Ethernet rates (< 100MB/s) given a reasonable disk subsystem. Bob -- Bob Friesenhahn bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/