From owner-freebsd-questions@freebsd.org Thu Oct 19 05:59:06 2017 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 E5421E2B8B8 for ; Thu, 19 Oct 2017 05:59:06 +0000 (UTC) (envelope-from matthew@FreeBSD.org) Received: from smtp.infracaninophile.co.uk (smtp.infracaninophile.co.uk [81.2.117.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "smtp.infracaninophile.co.uk", Issuer "infracaninophile.co.uk" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 764207FF1C for ; Thu, 19 Oct 2017 05:59:06 +0000 (UTC) (envelope-from matthew@FreeBSD.org) Received: from liminal.local (unknown [IPv6:2001:8b0:151:1:e1a9:cc14:47bb:9ffb]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: m.seaman@infracaninophile.co.uk) by smtp.infracaninophile.co.uk (Postfix) with ESMTPSA id 62767D5A7 for ; Thu, 19 Oct 2017 05:58:57 +0000 (UTC) Authentication-Results: smtp.infracaninophile.co.uk; dmarc=none (p=none dis=none) header.from=FreeBSD.org Subject: Re: Md based tmpfs with zfs root system. To: freebsd-questions@freebsd.org References: <20171018164559.GA3267@anza.vindaloo.com> From: Matthew Seaman Message-ID: Date: Thu, 19 Oct 2017 06:58:45 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171018164559.GA3267@anza.vindaloo.com> Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="aH8ooV5C7cd51C48lug0OG9Ono4n9nHjs" X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Oct 2017 05:59:07 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --aH8ooV5C7cd51C48lug0OG9Ono4n9nHjs Content-Type: multipart/mixed; boundary="mSjvxnoFQIQeBVHqSCgKepWoLLSu9awIr"; protected-headers="v1" From: Matthew Seaman To: freebsd-questions@freebsd.org Message-ID: Subject: Re: Md based tmpfs with zfs root system. References: <20171018164559.GA3267@anza.vindaloo.com> In-Reply-To: <20171018164559.GA3267@anza.vindaloo.com> --mSjvxnoFQIQeBVHqSCgKepWoLLSu9awIr Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: quoted-printable On 18/10/2017 17:45, Christopher Sean Hilton wrote: > Good day, >=20 > I've using a new system with root on zfs. I've traditionally used a > /dev/md* based tmpfs for /tmp. A little initial reading on the subject > shows an argument about this practice but I didn't find any threads > that provide a resolution. Furthermore, all the information that I > found which says that this is a bad idea dates from about FreeBSD-8.2, > and that's long obsolete. >=20 > What's the current resolution on this for a FreeBSD 11-STABLE user? > Should I avoid using a swap backed /dev/md based tmpfs filesystem for > /tmp? >=20 Using a tmpfs for /tmp is perfectly fine -- but you don't need to touch any /dev/md devices; just add a line like this to /etc/fstab: tmpfs /tmp tmpfs rw,mode=3D1777 0 0 I do this as standard on my machines, including in all jails. In fact, I think using a temporary swap backed filesystem for ephemeral data is an underused idea in FreeBSD: machines nowadays generally have much more swap configured than they will actually use, and that diskspace is otherwise wasted. Cheers, Matthew --mSjvxnoFQIQeBVHqSCgKepWoLLSu9awIr-- --aH8ooV5C7cd51C48lug0OG9Ono4n9nHjs Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQJ8BAEBCgBmBQJZ6D8bXxSAAAAAAC4AKGlzc3Vlci1mcHJAbm90YXRpb25zLm9w ZW5wZ3AuZmlmdGhob3JzZW1hbi5uZXQ2NTNBNjhCOTEzQTRFNkNGM0UxRTEzMjZC QjIzQUY1MThFMUE0MDEzAAoJELsjr1GOGkAT/RwP/15sjgJ8X0oCZ1Lcd/0dH7YL CuiyKNYiWQOm2ARMx7MQR08EgWI7VYNpjlM1Flfz/lSRmRt9j9t0D0VvOyNeBn6f 9/1Kz3J38yLP6umpxgWOu0wD+AdmPN8lJnlv1cIq+SnBNEFNnfNf5mDtLdh0mYGR kZM8f+ZNIM3Vg0dOFDrTfIkHnA99stljM0sI58Z7oOE8Yyi82XyD9nua62+PGkdS 42O5TpQR9TNY7RvxwMPoRXnNQCC7ClbBcLHCvwf8wmKtxELyO/zHzwLgUgVTgTwi xqSezqa2KFbBYI7B73CP9ekLRPZ6oJ/V7cS9zUQhSc6xNsOeKeUKE9xQg0aAU/Fd tvTCEw7LqB9fUi/g6++E1EmFevdxr//gG3RpS0Zpw9YDLzCh9NOUYUqj0pKLBN1e IPRp/MNkZGrKnCfNCTigfp7fu9w6ihTrFObHPofeYQxTTQGyf1x4GIdAN6qkcmWn s2NZ+JOPpgNe9RascXtBEZCsbz7EaEP/2gIhLAFHPIDGPFTSB/KrrYSqIQaajCqD XiuqUs6ankHJdWp2tL7+Qkt6r3QGZR3w3E4Jz22Qzd3crerw47DmB5P3suq1ogFz VgFv4bNVW70bya8lJ17g4tqMBET8R7yPO99K168SgKd+Jy5Dli8i6qLM90MGBgC7 Q9sEsve/6u7px2t0C3XR =wgLa -----END PGP SIGNATURE----- --aH8ooV5C7cd51C48lug0OG9Ono4n9nHjs--