From owner-freebsd-fs@freebsd.org Fri Dec 1 11:37:53 2017 Return-Path: Delivered-To: freebsd-fs@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 0E7EDDFD3B8 for ; Fri, 1 Dec 2017 11:37:53 +0000 (UTC) (envelope-from marek.salwerowicz@misal.pl) Received: from mail3.misal.pl (mail3.misal.pl [84.10.51.110]) (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 89DA67DF1E for ; Fri, 1 Dec 2017 11:37:52 +0000 (UTC) (envelope-from marek.salwerowicz@misal.pl) Received: from localhost (mail3.misal.pl [127.0.0.1]) by mail3.misal.pl (Postfix) with ESMTP id 6B2F61FE7 for ; Fri, 1 Dec 2017 12:30:36 +0100 (CET) X-Virus-Scanned: amavisd X-Spam-Flag: NO X-Spam-Score: -3 X-Spam-Level: X-Spam-Status: No, score=-3 tagged_above=-9999 required=8 tests=[ALL_TRUSTED=-1, BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1] autolearn=ham autolearn_force=no Authentication-Results: mail3.misal.pl (amavisd-new); dkim=pass (1024-bit key) header.d=misal.pl Received: from mail3.misal.pl ([127.0.0.1]) by localhost (mail3.misal.pl [127.0.0.1]) (amavisd-new, port 10024) with LMTP id uQEU0QQ2tWJu for ; Fri, 1 Dec 2017 12:30:35 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 mail3.misal.pl 1A809BD DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=misal.pl; s=misal.pl; t=1512127835; bh=rj0HSJh6VMzRO3EY0S3ONuUuLEpsaTfyk+w6MViEbCM=; h=From:Subject:To:Date:From; b=wQUvmkAp7V15aNmMSLCv1juyJtMbBFok986dlZObaYUT4a2a1tPpmJkIG9oe0mUBZ L1VKqpF3I2ofcpIrbCmXIORaID1RH22G+iobzy0IV82lidssE1SVyZ2Ab07ug4SW+0 cgiEcXHk+GAvqBupdnhohMpAu6agUBwLhAjSRfQ8= From: Marek Salwerowicz Subject: Reducing the ZVOL refreservation size? To: "freebsd-fs@freebsd.org" Message-ID: <811b1fb1-58ba-a8f6-238f-e52b0d392c0e@misal.pl> Date: Fri, 1 Dec 2017 12:30:34 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 Dec 2017 11:37:53 -0000 Hi list, My box is running FreeBSD 10.3-RELEASE-p11: FreeBSD storage2 10.3-RELEASE-p11 FreeBSD 10.3-RELEASE-p11 #0: Mon Oct 24 18:49:24 UTC 2016 root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC amd64 More than 3 years ago I created a 20 TB ZVOL, to be used as an iSCSI drive for Win2k8 Server. Currently the Server uses around 7 TB of the storage space. However, the total space consumed by the ZVOL is around 27TB (instead of desired 20TB). What I have noticed is that the 'refreservation' size value does not decrease while the 'referenced' size value increases. As I can predict, after filling the ZVOL with data, it will consume around 40 TB in total. Is it safe to reduce the 'refreservation' from 20 TB to eg. 15 TB?   So that there will be around 5TB of storage space freed? Please find below all details for the ZVOL: #zfs get all tank1/PROD/WIN-Drive NAME                   PROPERTY VALUE                  SOURCE tank1/PROD/WIN-Drive  type                  volume - tank1/PROD/WIN-Drive  creation              Wed May 21 10:53 2014 - tank1/PROD/WIN-Drive  used                  27.6T - tank1/PROD/WIN-Drive  available             26.9T - tank1/PROD/WIN-Drive  referenced            6.96T - tank1/PROD/WIN-Drive  compressratio         1.00x - tank1/PROD/WIN-Drive  reservation           none default tank1/PROD/WIN-Drive  volsize               20T local tank1/PROD/WIN-Drive  volblocksize          8K - tank1/PROD/WIN-Drive  checksum              on default tank1/PROD/WIN-Drive  compression           off default tank1/PROD/WIN-Drive  readonly              off default tank1/PROD/WIN-Drive  copies                1 default tank1/PROD/WIN-Drive  refreservation        20.6T local tank1/PROD/WIN-Drive  primarycache          all default tank1/PROD/WIN-Drive  secondarycache        all default tank1/PROD/WIN-Drive  usedbysnapshots       48.8G - tank1/PROD/WIN-Drive  usedbydataset         6.96T - tank1/PROD/WIN-Drive  usedbychildren        0 - tank1/PROD/WIN-Drive  usedbyrefreservation  20.6T - tank1/PROD/WIN-Drive  logbias               latency default tank1/PROD/WIN-Drive  dedup                 off default tank1/PROD/WIN-Drive  mlslabel - tank1/PROD/WIN-Drive  sync                  standard default tank1/PROD/WIN-Drive  refcompressratio      1.00x - tank1/PROD/WIN-Drive  written               18.0G - tank1/PROD/WIN-Drive  logicalused           6.96T - tank1/PROD/WIN-Drive  logicalreferenced     6.91T - tank1/PROD/WIN-Drive  volmode               default default tank1/PROD/WIN-Drive  snapshot_limit        none default tank1/PROD/WIN-Drive  snapshot_count        none default tank1/PROD/WIN-Drive  redundant_metadata    all default Thanks in advance for your help Cheers Marek -- Marek Salwerowicz