From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by finch.gentoo.org (Postfix) with ESMTPS id A4516139335 for ; Tue, 29 Jun 2021 13:57:12 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 36424E0875; Tue, 29 Jun 2021 13:57:04 +0000 (UTC) Received: from mout.gmx.net (mout.gmx.net [212.227.15.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 78963E0822 for ; Tue, 29 Jun 2021 13:57:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1624975011; bh=wq66fE61A+XTop+U3txE6FW4hiII+1Z4UJelRfLBmOs=; h=X-UI-Sender-Class:Date:From:To:Subject; b=lelVK4kYlFgBpmrYmPLwprNpWOSMzMG4ATgrLDXkrqBYJzteDu3zf8ncMlXt5nBAS AuGiy/T10kIIW1E793dS4zcTbS6qP2NyVcMuK90Kl/KWpnw1e/yh6i3AI2hgs17xeu KJqMxhESwwIzpTjcOIA6wGauueelnpbhqq4uX1HU= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from moby ([92.117.49.17]) by mail.gmx.net (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1M1HZo-1lvU8v2f1u-002oqx for ; Tue, 29 Jun 2021 15:56:51 +0200 Date: Tue, 29 Jun 2021 15:56:49 +0200 From: Frank Steinmetzger To: gentoo-user@lists.gentoo.org Subject: [gentoo-user] [OT] Using an odd number of drives in ZFS RaidZ Message-ID: Mail-Followup-To: gentoo-user@lists.gentoo.org Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org X-Auto-Response-Suppress: DR, RN, NRN, OOF, AutoReply MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="YCrgOF7r4v4+t3Kw" Content-Disposition: inline User-Agent: Mutt 2.1; VIM - Vi IMproved 8.2 X-Provags-ID: V03:K1:5k6cgGVwCedZ2IiWbTWzJHwdElQfuz0oPgKKAnKMv2vSKDNFkb2 srAaEWGWRlQ17lnrGNYvYcdt80sYhMn8if6JuwCQ72vh8VMlJmyBi+5dqK6skQV7VEbizWp iNUN6j7YEE887b8MV6aQtzX3UE3djqeul5dV5X8HpqraZZv5/24nNeU2bWQbcZFMnrRiVDq m1QwgUrsP1DO8Ol4DEbWw== X-Spam-Flag: NO X-UI-Out-Filterresults: notjunk:1;V03:K0:flDzEwq517A=:RYEwoYCJh4nxafn3rCcywY ldccoaPdN4TLe9DMr+qqSd8FjEATap8SoNrV5ZUwPDob4QEx5JTLOmdn1Iys3/ZCCwmCQKaUE GfZNYciLzJRuBMxA8Dy+esYsLQff7/kHlUSN4oIaUKRAW0YMetCcB2e6kcA3noTok1Q/UxMW3 K4ZryeEs9joeskP3LRikTNvBt+V/cRo17M/wtW3sr5HDjnndWzk5VBLEXwQ9h8V6PXNpRAx0h REjfvEoyHd/kSjz2N6JKpbTVqpwXUKA5WGPDOGo5VwroUUXfWkfU0bbEqITcZR+m3oVdCX0Nk XYciGBXm7l+I04HC3/Ydse1rII4OinTHw3uQLb0WECkWObuMDVab4KQ2WtWotFxjnItN/sFW9 nZN2wBh5qWhzifVa7hc1SKIplbEOBmDuROdvbm7czc63b13nPC3ENNiNHBXoe/GU0ISObjV91 3bPKULPrSRjg7r2qPfueYGyKaXbYFNTYdZgD04oDAznPZ/K8EQ/sHzu9ypHdsim1aqCj2pc9R UXDxTr6+OOj0v2J+n7M/FcS4rWuUhrFhX6jRd5ZxyYSDk1wzCUikww9W0/T6GgxQk5wIgI/UD +3lg+aohXq/xrxs2PPy1ITu2CTvMKS7aQTr1lKJ8EpRPEOK0u8dOd8K503XTeEXQe4vDZUOIG OZxsrP8PkHOnHaaaXBQ46H8QJL56W5HFmceQLVJ6uNsaf0Eo+nJR3F4c933ZZAXPoy6uPtyPR Zbf+o1xwnIzBkXz9h9rGfI7NmHKP50xXCDmk9mo48mgSAkiZi9MzJRgkU5oNS326DirlBcCzR 9qO9uqw/afJGGoi8+zx5d5uSLBgX3zhMOybzbJyAvHyfTGR9IFoUejJrLey5MbB2A6A2vmYtD uvAZDF3/S4pD689EnlZrnyKwl9K1TTWX7LVy0L50Lzd5xWKuKNoTaTiNlvn0hjcTWS1fTY6Vb sPJjwLj/ReSFvHujAJ67sOQ3G0PMZaphR5o5hnNjLoF973KCTCCIHidE2/KPDXfygrG+jlQiq Er/5iR6o85WRXhv20VARMl7NkBa0brtyCHGcHT0tZJNzhpPgBnC5gFacgYJORNRb+f6RXPDK6 4cvqKEQWmTTDg8VucTMtY31LBV7GOtYFHVG X-Archives-Salt: f05d33e9-b49a-4393-85c1-c75e11196b63 X-Archives-Hash: 50688b642ec3413ce7691e22929ee8ca --YCrgOF7r4v4+t3Kw Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello fellows This is not really a Gentoo question, but at least my NAS (which this mail is about) is running Gentoo. :) There are some people amongst this esteemed group that know their stuff about storage and servers and things, so I thought I might try my luck here. I=E2=80=99ve already looked on the Webs, but my question is a wee bit speci= fic and I wasn=E2=80=99t able to find the exact answer (yet). And I=E2=80=99m a bit h= esitant to ask this newbie-ish question in a ZFS expert forum. ;-) Prologue: Due to how records are distributed across blocks in a parity-based ZFS vdev, it is recommended to use 2^n data disks. Technically, it is perfectly fine to deviate from it, but for performance reasons (mostly space efficiency) it is not the recommended way. That=E2=80=99s because the (default) maximum re= cord size of 128 k itself is a power of 2 and thus can be distributed evenly on all drives. At least that=E2=80=99s my understanding. Is that correct? So here=E2=80=99s the question: If I had three data drives, (c|w)ould I get around that problem by setting a record size that is divisible by 3, like 96 k, or even 3 M? Here=E2=80=99s the background of my question: Said NAS is based on a Mini-ITX case which has only four drive slots (which is the most common configuration for a case of this formfactor). I started with two 6 TB drives, running in a mirror configuration. One year later space was running out and I filled the remaining slots. To maximise reliability, I went with RaidZ2. I reached 80 % usage (which is the recommended maximum for ZFS) and am now evaluating my options for the coming years. 1) Reduce use of space by re-encoding. My payload is mainly movies, among which are 3 TB of DVDs which can be shrunk by at least =E2=85=94 by re-e= ncoding. =E2=86=92 this takes time and computing effort, but is a long-term goal = anyway. 2) Replace all drives with bigger ones. There are three counter arguments: =E2=80=A2 1000 =E2=82=AC for four 10 TB drives (the biggest size availab= le w/o helium) =E2=80=A2 they are only available with 7200 rpm (more power, noise and h= eat) =E2=80=A2 I am left with four perfectly fine 6 TB drives 3) Go for 4+2 RaidZ2. This requires a bigger case (with new PSU due to different form factor) and a SATA expansion card b/c the Mobo only has six connectors (I need at least one more for the system drive), costing 250 =E2=82=AC plus drives. 4) Convert to RaidZ1. Gain space of one drive at the cost of resilience. I can live with the latter; the server only runs occasionally and not for very long at a time. *** This option brings me to my question above, because it is easy to achieve and costs no =E2=82=AC=E2=82=AC=E2=82=AC. --=20 Gr=C3=BC=C3=9Fe | Greetings | Qapla=E2=80=99 Please do not share anything from, with or about me on any social network. In this sentance are definately three error=E2=80=99s! --YCrgOF7r4v4+t3Kw Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEVbE9o2D2lE5fhoVsizG+tUDUMMoFAmDbJp8ACgkQizG+tUDU MMpRdg/7Bkgh8tMlvo9YN45/kV8OE5OiqezOfw7a2E69e2B802qE+VBj3HH7PJIP hrg0LwIf/e6CuWGyNcx64dbS2R7t/wDcdoCROtdJY7hcVlFcGiO6VND02T/8Z1q2 38rj+48I8kCN9y7H1313YJkrzdQNaLR/BfpSFUitoST4Vo1jnPJ++U5rTnfyvz7q avCpeijgezk9em8B+/yVBssF1Gk+3EhoUENJtKFHzkcww6WSbeGgZqXWw3XzjVkz le8hJZdLtDljAQIhgAqJ+pbWoz4zoQAAVR4C0VuUkH2O4S6sXadyLQSKkGGi5uR/ 1vQNTfZB9Z04kzBE3hj52YDjOR2u1zpok/9cZ2t2gZSi4Jw86W7q8vrc7ByyQOIa +XtSV6EkjHKysftUxUbm5KDqRI1oUfaho8Jb8aWRPIjKlFywP59otZcPqGy86LKT 5nKFR0nWtzHSQeXNSOpRhoNGRulT2w1/+0rlim/bEHkp6umPQuAvTuXoAzgpoCZG mbh79/8z1hZA9BXihLSbSavBab9h7yHjQLbLTiCYhC7mVsiE5n7SZS8XEQdYTc3d LiOaGSREp9Cn15/KNdKwUdsvT8Ky/7+bHx3RpIx8xF2uDGdD97OlFuf/2e6ccV/x 9iumu3sdpWxTYhX48MblCbEJJkTlGLvu/DJJlKrtqQRowhRi2+Y= =MStp -----END PGP SIGNATURE----- --YCrgOF7r4v4+t3Kw--