Date: Mon, 8 Apr 2019 20:55:59 -0400 From: Alexander Motin <mav@FreeBSD.org> To: Eugene Grosbein <eugen@grosbein.net>, "Kevin P. Neal" <kpn@neutralgood.org>, Peter Jeremy <peter@rulingia.com> Cc: freebsd-fs@freebsd.org, freebsd-stable@freebsd.org, tech-lists <tech-lists@zyxst.net>, freebsd-geom@freebsd.org Subject: Re: about zfs and ashift and changing ashift on existing zpool Message-ID: <acb6eb40-3477-aedc-502e-87bb191a4b5b@FreeBSD.org> In-Reply-To: <9590cb82-64be-a2f9-a812-36f0ea324e4d@grosbein.net> References: <20190407153639.GA41753@rpi3.zyxst.net> <20190408212822.GD13734@server.rulingia.com> <20190409000009.GA65388@neutralgood.org> <9590cb82-64be-a2f9-a812-36f0ea324e4d@grosbein.net>
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On 08.04.2019 20:21, Eugene Grosbein wrote: > 09.04.2019 7:00, Kevin P. Neal wrote: > >>> My guess (given that only ada1 is reporting a blocksize mismatch) is that >>> your disks reported a 512B native blocksize. In the absence of any override, >>> ZFS will then build an ashift=9 pool. > > [skip] > >> smartctl 7.0 2018-12-30 r4883 [FreeBSD 11.2-RELEASE-p4 amd64] (local build) >> Copyright (C) 2002-18, Bruce Allen, Christian Franke, www.smartmontools.org >> >> === START OF INFORMATION SECTION === >> Vendor: SEAGATE >> Product: ST2400MM0129 >> Revision: C003 >> Compliance: SPC-4 >> User Capacity: 2,400,476,553,216 bytes [2.40 TB] >> Logical block size: 512 bytes >> Physical block size: 4096 bytes > > Maybe it't time to prefer "Physical block size" over "Logical block size" in relevant GEOMs > like GEOM_DISK, so upper levels such as ZFS would do the right thing automatically. No. It is a bad idea. Changing logical block size for existing disks will most likely result in breaking compatibility and inability to read previously written data. ZFS already uses physical block size when possible -- on pool creation or new vdev addition. When not possible (pool already created wrong) it just complains about it, so that user would know that his configuration is imperfect and he should not expect full performance. -- Alexander Motin
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