Date: Wed, 21 Oct 2015 16:35:25 +0200 From: Julien Cigar <jcigar@ulb.ac.be> To: Adam Vande More <amvandemore@gmail.com> Cc: "Brandon J. Wandersee" <brandon.wandersee@gmail.com>, FreeBSD Questions <freebsd-questions@freebsd.org>, krad <kraduk@gmail.com> Subject: Re: gjournal and TRIM: A safe combination? Message-ID: <20151021143525.GX87605@mordor.lan> In-Reply-To: <CA%2BtpaK0ezoi7wBBD9VZwREq9Qp0YaJNfJY42=tZAYi5VSL8rCA@mail.gmail.com> References: <867fmh12nq.fsf@WorkBox.Home> <CALfReyfg-71nCg4K0dKmUK-YmZ8yi0ppeGGv4WOD-2Mt8NP9HQ@mail.gmail.com> <86pp081glq.fsf@WorkBox.Home> <CA%2BtpaK0ezoi7wBBD9VZwREq9Qp0YaJNfJY42=tZAYi5VSL8rCA@mail.gmail.com>
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--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. However, many electrons were terribly inconvenienced. --w8QetmdSDwT395M8 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCgAGBQJWJ6KpAAoJEAi2KiTKQR5pOTwP/0P1K8zOaNXrXbAIS6UGGmz8 6mpUoYTOmCZqnGsElEatzHnpUBppIcUlqtV9h4nyeKnjLq4K391kg1dRs2nHEOoH GEQwnoerRBNWjn/Uj4TlaRA80s76RoVBn8UAgggdFx85VnL7ODXWYy42ma74Qt/Y RtxIWxSbXp4spKbGOQVSqMwUYi6q3GwNzuI3vobJHRdFOw++HkWl1oCh0Z2fs1ND VcTCp6cdK4uEPhX5J+WFSm+B98IHp29CznWh7PH7R7plHW3pTf7rBejxS1Fezz1c gWOj+wVf1LsFtOkETxDp/Yp9chTsXsCdW3yyVIxBKI8USpU9YIlHBawKJu/Hv58k dyEwyNGEuZ2ckYyyCBfAWB1oEuH1gSq7sPkmuvO9tpGo1ZxKTHzMQFItUsBr4ki1 LRnWc995sfwnpHc23HytDfhbEvJGhN/mZlg6ks/rhsftsOKaWJfBx31t0dju+CaK cX7Wbc4mway/xbaSYvkotJ3SldBLiHGotimmFdWsg5w3erC/89VjqoS/19w95Tg9 sxg92tlnrz2gGh594CvqAmbzaAzNWP/oJuAgY7TOff1FQbHrsyqNXNTetdEMJHi9 PfpZaa+GkunPSziRCGUl8m6ra1SbiLnBkTt111zJiJqFOjL0VfHWTZ7xh/rM1hB0 tgwdX7I3aiNQWh2/JNPn =Fy/C -----END PGP SIGNATURE----- --w8QetmdSDwT395M8--
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