Date: Mon, 8 Apr 2019 21:25:43 -0400 From: Michael Butler <imb@protected-networks.net> To: Alexander Motin <mav@FreeBSD.org>, Eugene Grosbein <eugen@grosbein.net>, "Kevin P. Neal" <kpn@neutralgood.org>, Peter Jeremy <peter@rulingia.com> Cc: freebsd-fs@freebsd.org, freebsd-geom@freebsd.org, freebsd-stable@freebsd.org, tech-lists <tech-lists@zyxst.net> Subject: Re: about zfs and ashift and changing ashift on existing zpool Message-ID: <d9eb4255-b055-3b38-cdfa-defe089ae6b5@protected-networks.net> In-Reply-To: <acb6eb40-3477-aedc-502e-87bb191a4b5b@FreeBSD.org> References: <20190407153639.GA41753@rpi3.zyxst.net> <20190408212822.GD13734@server.rulingia.com> <20190409000009.GA65388@neutralgood.org> <9590cb82-64be-a2f9-a812-36f0ea324e4d@grosbein.net> <acb6eb40-3477-aedc-502e-87bb191a4b5b@FreeBSD.org>
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On 2019-04-08 20:55, Alexander Motin wrote: > 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. And some drives just present 512 bytes for both .. no idea if this is consistent with the underlying silicon :-( I built a ZFS pool on it using 4k blocks anyway. smartctl 7.0 2018-12-30 r4883 [FreeBSD 13.0-CURRENT amd64] (local build) Copyright (C) 2002-18, Bruce Allen, Christian Franke, www.smartmontools.org === START OF INFORMATION SECTION === Device Model: WDC WDS100T2B0A-00SM50 Serial Number: 1837B0803409 LU WWN Device Id: 5 001b44 8b99f7560 Firmware Version: X61190WD User Capacity: 1,000,204,886,016 bytes [1.00 TB] Sector Size: 512 bytes logical/physical Rotation Rate: Solid State Device Form Factor: 2.5 inches Device is: Not in smartctl database [for details use: -P showall] ATA Version is: ACS-4 T13/BSR INCITS 529 revision 5 SATA Version is: SATA 3.3, 6.0 Gb/s (current: 6.0 Gb/s) Local Time is: Mon Apr 8 21:22:15 2019 EDT SMART support is: Available - device has SMART capability. SMART support is: Enabled AAM feature is: Unavailable APM level is: 128 (minimum power consumption without standby) Rd look-ahead is: Enabled Write cache is: Enabled DSN feature is: Unavailable ATA Security is: Disabled, frozen [SEC2] Wt Cache Reorder: Unavailable imb
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