From owner-freebsd-fs@FreeBSD.ORG Fri Feb 15 09:16:14 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115]) by hub.freebsd.org (Postfix) with ESMTP id E6E4B8E7 for ; Fri, 15 Feb 2013 09:16:14 +0000 (UTC) (envelope-from delphij@gmail.com) Received: from mail-lb0-f179.google.com (mail-lb0-f179.google.com [209.85.217.179]) by mx1.freebsd.org (Postfix) with ESMTP id 50E1AC2C for ; Fri, 15 Feb 2013 09:16:14 +0000 (UTC) Received: by mail-lb0-f179.google.com with SMTP id j14so2397869lbo.24 for ; Fri, 15 Feb 2013 01:16:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; bh=RvcBlzpu8O3uE5Aya3QystKNScgFe3rpGZ3apDY/kxA=; b=f5AzOHRWUcr0Dxv0ggDfBva1wGhMbCy5Gfv3SIRGX3vSM0ttj5oJ7DgrvNXD3zP3gf 2LR9YWTHig9+FotcureUqs1uv0Bw4YF/LDadhFe9BkWWdDPBrqHz8z39uS7Eh8Qo5Ezf F4r5GV7YfRwSD9W0TRaTPayhkHsER+/ifV2JgfCdlM39gMCe6o8laSyfLdlZk2J54guO w+/rTu8Ioe0hUekotEJSKiaAvAE2hTtOhN2OBnqGZwLGjrDMZOVoZix2Mi/8k/v8rwd+ TYISuQNsQyKfEq3f28xpGUoNsTGY/CFdj8HsHjwErpcOs5Kb3m6kY7MUat1XwRdEFiNZ 2ySg== MIME-Version: 1.0 X-Received: by 10.112.88.10 with SMTP id bc10mr1798878lbb.70.1360919773085; Fri, 15 Feb 2013 01:16:13 -0800 (PST) Received: by 10.114.29.165 with HTTP; Fri, 15 Feb 2013 01:16:12 -0800 (PST) In-Reply-To: References: Date: Fri, 15 Feb 2013 01:16:12 -0800 Message-ID: Subject: Re: Crazy ZFS ZIL options: md(4) umass(4) From: Xin LI To: grarpamp Content-Type: text/plain; charset=UTF-8 Cc: freebsd-fs X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 15 Feb 2013 09:16:15 -0000 On Fri, Feb 15, 2013 at 1:00 AM, grarpamp wrote: > I have thousands of small files being written most under 8KiB, they > either end up being removed or combined in various ways to > produce a set of data that is stored long term. I also have > tens of 10-50MiB files similarly, but rarely. It's not fully clear > to me the benefits of a split ZIL. Some say a split ZIL will ward > off some fragmentation, which pushing over 80% I'm sure to see > otherwise. Plus a speed boost if on faster media. And maybe > even no need to commit some ZIL to disk as small files are > removed before ZFS decides to aggregate? > > Anyway, use case aside, I can put 1GiB of ram as ZIL.Same for 32GiB USB. > RAM is obviously fast and power fail prone. > USB is slow and power safe. > Either could be mirrored, 2xRAM, 2xUSB. > > - If I lose power on RAM, will the disk still be consistent? > - What data integrity does ZIL have? None? ZFS dataset's sha256? > - Any production experiences with this crazy ideas? Why don't just set sync=disabled? Cheers, -- Xin LI https://www.delphij.net/ FreeBSD - The Power to Serve! Live free or die