From owner-freebsd-stable@freebsd.org Wed Apr 4 07:41:00 2018 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 3EE69F9A9AC for ; Wed, 4 Apr 2018 07:41:00 +0000 (UTC) (envelope-from hausen@punkt.de) Received: from kagate.punkt.de (kagate.punkt.de [217.29.33.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id BA054694E9 for ; Wed, 4 Apr 2018 07:40:59 +0000 (UTC) (envelope-from hausen@punkt.de) Received: from hugo10.ka.punkt.de (hugo10.ka.punkt.de [217.29.44.10]) by gate2.intern.punkt.de with ESMTP id w347ZWjC098324; Wed, 4 Apr 2018 09:35:32 +0200 (CEST) Received: from [217.29.44.241] ([217.29.44.241]) by hugo10.ka.punkt.de (8.14.2/8.14.2) with ESMTP id w347ZUK4027602; Wed, 4 Apr 2018 09:35:31 +0200 (CEST) (envelope-from hausen@punkt.de) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: another question about zfs compression numbers From: "Patrick M. Hausen" In-Reply-To: <52b1c557-bdb5-3b9f-1ce1-32f698ae982c@zhegan.in> Date: Wed, 4 Apr 2018 09:35:30 +0200 Cc: freebsd-stable@freebsd.org Content-Transfer-Encoding: quoted-printable Message-Id: <8A5C86CA-C959-4DFF-9168-DD94CF46AC91@punkt.de> References: <52b1c557-bdb5-3b9f-1ce1-32f698ae982c@zhegan.in> To: "Eugene M. Zheganin" X-Mailer: Apple Mail (2.3273) X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 Apr 2018 07:41:00 -0000 Hi all, > Am 04.04.2018 um 09:21 schrieb Eugene M. Zheganin : > I'm just trying to understand these numbers: >=20 > file size is 232G, it's actual size on the lz4-compressed dataset is = 18G, so then why is the compressratio only 1.86x ? And why logicalused = is 34.2G ? On one hand, 34.2G exactlyfits to the 1.86x compresstaio, but = still I don't get it. dataset is on raidz, 3 spans across 5 disk vdevs, = with total of 15 disks if it matters: A sparse file, possibly? The ZFS numbers refer to blocks. "Skipping" = zeroes at the VFS layer is not taken into account as fas as I know. Seriously, how = should it? If I'm not mistaken, ZFS will never get to see these empty blocks. Patrick --=20 punkt.de GmbH Internet - Dienstleistungen - Beratung Kaiserallee 13a Tel.: 0721 9109-0 Fax: -100 76133 Karlsruhe info@punkt.de http://punkt.de AG Mannheim 108285 Gf: Juergen Egeling