From owner-freebsd-stable@freebsd.org Wed Apr 4 07:46:38 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 E9CA1F9AEFB for ; Wed, 4 Apr 2018 07:46:37 +0000 (UTC) (envelope-from eugene@zhegan.in) Received: from elf.hq.norma.perm.ru (mail.norma.perm.ru [IPv6:2a00:7540:1::5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mail.norma.perm.ru", Issuer "Vivat-Trade UNIX Root CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 4F9E0699CD for ; Wed, 4 Apr 2018 07:46:37 +0000 (UTC) (envelope-from eugene@zhegan.in) Received: from bsdrookie.norma.com. (asterisk.enaza.ru [91.237.76.254]) by elf.hq.norma.perm.ru (8.15.2/8.15.2) with ESMTPS id w347kXde025317 (version=TLSv1.2 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Wed, 4 Apr 2018 12:46:33 +0500 (YEKT) (envelope-from eugene@zhegan.in) Subject: Re: another question about zfs compression numbers To: "Patrick M. Hausen" Cc: freebsd-stable@freebsd.org References: <52b1c557-bdb5-3b9f-1ce1-32f698ae982c@zhegan.in> <8A5C86CA-C959-4DFF-9168-DD94CF46AC91@punkt.de> From: "Eugene M. Zheganin" Message-ID: <60635355-c0f3-9c3e-2375-7637bb073d87@zhegan.in> Date: Wed, 4 Apr 2018 12:46:33 +0500 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <8A5C86CA-C959-4DFF-9168-DD94CF46AC91@punkt.de> Content-Type: text/plain; charset=koi8-r; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Spamd-Result: default: False [-998.10 / 25.00] WHITELISTED_IPS(-999.00)[91.237.76.254] AUTH_NA(1.00)[] RCVD_COUNT_TWO(0.00)[2] MID_RHS_MATCH_FROM(0.00)[] DMARC_NA(0.00)[zhegan.in] FROM_EQ_ENVFROM(0.00)[] ARC_NA(0.00)[] ASN(0.00)[asn:57973, ipnet:91.237.76.0/24, country:RU] FROM_HAS_DN(0.00)[] R_SPF_NA(0.00)[] TO_MATCH_ENVRCPT_ALL(0.00)[] MIME_GOOD(-0.10)[text/plain] RCVD_TLS_ALL(0.00)[] RCPT_COUNT_TWO(0.00)[2] TO_DN_SOME(0.00)[] R_DKIM_NA(0.00)[] IP_SCORE(0.00)[ip: (-9.88), ipnet: 91.237.76.0/24(-7.81), asn: 57973(-4.88), country: RU(0.12)] X-Rspamd-Server: localhost X-Rspamd-Scan-Time: 0.63 X-Rspamd-Queue-ID: w347kXde025317 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 07:46:38 -0000 Hi, On 04.04.2018 12:35, Patrick M. Hausen wrote: > Hi all, > >> Am 04.04.2018 um 09:21 schrieb Eugene M. Zheganin : >> I'm just trying to understand these numbers: >> >> 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. > Looks so, thanks. Although it's a mysql tablespace file. But yeah, in hex viewer looks like it's filled with zeroes in many places. Eugene.