From nobody Sat Apr 22 18:20:29 2023 X-Original-To: questions@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4Q3fpB3ydZz465fG for ; Sat, 22 Apr 2023 18:20:34 +0000 (UTC) (envelope-from paul@gromit.dlib.vt.edu) Received: from gromit.dlib.vt.edu (gromit.dlib.ipv6.vt.edu [IPv6:2001:468:c80:a103:2:5000:5555:5555]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4Q3fp93Tkvz4kqM for ; Sat, 22 Apr 2023 18:20:33 +0000 (UTC) (envelope-from paul@gromit.dlib.vt.edu) Authentication-Results: mx1.freebsd.org; none Received: from mbp-2012.gromit23.net (unknown [73.99.214.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by gromit.dlib.vt.edu (Postfix) with ESMTPSA id 820603EF9C; Sat, 22 Apr 2023 14:20:30 -0400 (EDT) Content-Type: text/plain; charset=us-ascii List-Id: User questions List-Archive: https://lists.freebsd.org/archives/freebsd-questions List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-questions@freebsd.org X-BeenThere: freebsd-questions@freebsd.org Mime-Version: 1.0 (Mac OS X Mail 13.4 \(3608.120.23.2.7\)) Subject: Re: ZFS on root with dedupe From: Paul Mather In-Reply-To: Date: Sat, 22 Apr 2023 14:20:29 -0400 Cc: questions@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: <21DC1470-EFCF-481D-BD3E-0C1C2BD9B5E1@gromit.dlib.vt.edu> References: <361F0E2D-C885-4491-9D66-CC077CEE1BB4@gromit.dlib.vt.edu> To: Andrea Venturoli X-Mailer: Apple Mail (2.3608.120.23.2.7) X-Rspamd-Queue-Id: 4Q3fp93Tkvz4kqM X-Spamd-Bar: ---- X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:1312, ipnet:2001:468:c80::/48, country:US] X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-ThisMailContainsUnwantedMimeParts: N On Apr 22, 2023, at 1:52 PM, Andrea Venturoli wrote: > On 4/22/23 17:46, Paul Mather wrote: >=20 >> Deduplication is a per-fileset option >=20 > Oh! > I always thought it was a per-pool setting!!! > Did it change, perhaps after the switch to OpenZFS? I believe it has always been a per-fileset property. I think it is seen = as a "per-pool" setting because of the performance impact it can have on = the entire pool by enabling it on a fileset. ( > In fact the handbook says: >=20 >> To activate deduplication, set the dedup property on the target pool: >> # zfs set dedup=3Don pool >=20 > Isn't this incoherent? > I mean: > zfs set ... *dataset* > *zpool* set ... pool >=20 > Should it be corrected? The handbook appears out of date in this case. Even the example, as you = point out, is confusing because it references a zfs(8) command, which = acts upon filesets. For 13-STABLE (and the most recent 13.2-RELEASE), the zfsconcepts(7) and = zfsprops(7) manual pages both refer to deduplication being enabled for a = "file system" or "dataset". The zfsprops(7) manual page includes the = "dedup" property in per-fileset (or dataset as the manual page calls it) = properties: "Configures deduplication for a dataset." The = zfsconcepts(7) manual page states, "If a file system has the dedup = property enabled, duplicate data blocks are removed synchronously." I = interpret "file system" to be the same as fileset/dataset. These are = fileset/dataset properties, not pool properties. It's difficult to keep the FreeBSD Handbook accurate because it = potentially covers many simultaneous supported versions of FreeBSD. I = always treat the manual pages for an installed FreeBSD version to be = more accurate than the Handbook. Cheers, Paul.