From owner-freebsd-questions@freebsd.org Wed Oct 21 14:36:42 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 A12B5A1BE38 for ; Wed, 21 Oct 2015 14:36:42 +0000 (UTC) (envelope-from jcigar@ulb.ac.be) Received: from relaygateway02.edpnet.net (relaygateway02.edpnet.net [212.71.1.211]) (using TLSv1 with cipher RC4-SHA (128/128 bits)) (Client CN "*.edpnet.net", Issuer "Go Daddy Secure Certificate Authority - G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id D6C5B886 for ; Wed, 21 Oct 2015 14:36:40 +0000 (UTC) (envelope-from jcigar@ulb.ac.be) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AnAGAKihJ1ZNbXNd/2dsb2JhbABdgzZUb79rFwqFM0oCgUNNAQEBAQEBgQuELgEBBAEBASArCBgLEAsYCRMOAgIPBQ0GAQkIJAgHBAEcBId6AxYJsFWOGQ1HhDcBAQEHAQEBARYJhneEfoJQgWsBAVAHgmmBRQWFRpBehRmFHDFDgW4IgViSfYNdg29jghEdgVc8NAeEIIFAAQEB X-IPAS-Result: AnAGAKihJ1ZNbXNd/2dsb2JhbABdgzZUb79rFwqFM0oCgUNNAQEBAQEBgQuELgEBBAEBASArCBgLEAsYCRMOAgIPBQ0GAQkIJAgHBAEcBId6AxYJsFWOGQ1HhDcBAQEHAQEBARYJhneEfoJQgWsBAVAHgmmBRQWFRpBehRmFHDFDgW4IgViSfYNdg29jghEdgVc8NAeEIIFAAQEB X-IronPort-AV: E=Sophos;i="5.17,712,1437429600"; d="asc'?scan'208";a="344620081" Received: from 77.109.115.93.adsl.dyn.edpnet.net (HELO mordor.lan) ([77.109.115.93]) by relaygateway02.edpnet.net with ESMTP/TLS/DHE-RSA-AES256-SHA; 21 Oct 2015 16:35:26 +0200 Date: Wed, 21 Oct 2015 16:35:25 +0200 From: Julien Cigar To: Adam Vande More Cc: "Brandon J. Wandersee" , FreeBSD Questions , krad Subject: Re: gjournal and TRIM: A safe combination? Message-ID: <20151021143525.GX87605@mordor.lan> References: <867fmh12nq.fsf@WorkBox.Home> <86pp081glq.fsf@WorkBox.Home> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="w8QetmdSDwT395M8" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) 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 14:36:42 -0000 --w8QetmdSDwT395M8 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Oct 21, 2015 at 09:15:33AM -0500, Adam Vande More wrote: > On Wed, Oct 21, 2015 at 8:44 AM, Brandon J. Wandersee < > brandon.wandersee@gmail.com> wrote: >=20 > > I thought the opposite, myself. `gjournal` has its own section in the > > Handbook, while SU+J isn't even mentioned. >=20 >=20 > 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. >=20 > 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. >=20 >=20 >=20 > > 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. > > >=20 > There is a fundamental difference between them. Don't you think you shou= ld > investigate the differences prior to deciding what to use? >=20 > 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. to resume: SU =3D metadata consistency SU+J =3D journaled metadata consistency=20 gjournal =3D metadata + data consistency (block based) Correct me if I'm wrong but, unless there is a bug in Soft Updates (SU), your FS will, in theory, never be corrupted with SU only =2E=20 The main advantage of SU+J over SU is to avoid a fsck at boot if the FS=20 is not clean. Note that SU+J almost never worked for me and disabling SU+J (tunefs -j disable) is the first thing I do after an installation. >=20 > --=20 > Adam > _______________________________________________ > freebsd-questions@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.o= rg" --=20 Julien Cigar Belgian Biodiversity Platform (http://www.biodiversity.be) PGP fingerprint: EEF9 F697 4B68 D275 7B11 6A25 B2BB 3710 A204 23C0 No trees were killed in the creation of this message. 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