From owner-freebsd-questions@freebsd.org Wed Oct 21 14:15:35 2015 Return-Path: Delivered-To: freebsd-questions@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 5A7EAA1B72B for ; Wed, 21 Oct 2015 14:15:35 +0000 (UTC) (envelope-from amvandemore@gmail.com) Received: from mail-wi0-x236.google.com (mail-wi0-x236.google.com [IPv6:2a00:1450:400c:c05::236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id DDF74F6D for ; Wed, 21 Oct 2015 14:15:34 +0000 (UTC) (envelope-from amvandemore@gmail.com) Received: by wicll6 with SMTP id ll6so93173596wic.0 for ; Wed, 21 Oct 2015 07:15:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=5USv6YHzt3WfAwJvK5FuJassnGTt5N7s+Phdcj6O7WY=; b=cCw43ZnH1oFHY7ZmODltv1cvFh6pEL04TlqqNq9yAFEEdAIDjEc60Y++ExqMHg7A2g HGLUZufBgTpFhezMEFC+ZY4+elljfhaRG5SIef+NKHsnGh/FGOWvY85E3v+yp78wHGup QrzDKOZWBM6zRfE8Tk3jw5MpQ5n3Y+UP+srXjab8D9lAcwsRivFSRNHgvB0SjzgrMMvY ujN6PREXaO/UUC2if1UhXp3TqhiXxT50KYZvu4onIY+DGdKWVHUv4uxGptv++/bSpzMX 2WfMa6thzCLUj7GYnWrwYiOuG+1iSINYXWFfduvsEzjbX9OgycWemotJTnJ6rigk4bj7 UvZg== MIME-Version: 1.0 X-Received: by 10.181.13.11 with SMTP id eu11mr4552621wid.10.1445436933129; Wed, 21 Oct 2015 07:15:33 -0700 (PDT) Received: by 10.194.16.231 with HTTP; Wed, 21 Oct 2015 07:15:33 -0700 (PDT) In-Reply-To: <86pp081glq.fsf@WorkBox.Home> References: <867fmh12nq.fsf@WorkBox.Home> <86pp081glq.fsf@WorkBox.Home> Date: Wed, 21 Oct 2015 09:15:33 -0500 Message-ID: Subject: Re: gjournal and TRIM: A safe combination? From: Adam Vande More To: "Brandon J. Wandersee" Cc: krad , FreeBSD Questions Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Oct 2015 14:15:35 -0000 On Wed, Oct 21, 2015 at 8:44 AM, Brandon J. Wandersee < brandon.wandersee@gmail.com> wrote: > I thought the opposite, myself. `gjournal` has its own section in the > Handbook, while SU+J isn't even mentioned. Unfortunately, this is not a safe assumption. The handbook is maintained by volunteers. The volunteers generally do a pretty good job, but are a few negatives of this approach. They aren't generally interested in updating old documentation which doesn't directly apply to them. The provided documentation is how they think it should be done: right, wrong or somewhere in-between. A lot of things don't get the attention they deserve like SU+J, GELI over GBDE, and in-kernel NAT w/ FreeBSD single native firewall ipfw. > I also thought there was > something fundamentally different about them--like SU+J simply maintains > filesystem integrity, while gjournal actually protects files from the > write hole as well as protecting the filesystem. I could be wrong. > There is a fundamental difference between them. Don't you think you should investigate the differences prior to deciding what to use? It's not at clear what your goal is here. Do you want to minimize writes to the ssd or do you want to ensure the fs is always consistent from both a meta-data and data perspective. These options are mutually exclusive in the parameters you've laid out. -- Adam