Date: Fri, 05 Jul 2013 13:37:58 +0300 From: Daniel Kalchev <daniel@digsys.bg> To: freebsd-fs@freebsd.org Subject: Re: Slow resilvering with mirrored ZIL Message-ID: <51D6A206.2020303@digsys.bg> In-Reply-To: <3CFB4564D8EB4A6A9BCE2AFCC5B6E400@multiplay.co.uk> References: <CABBFC07-68C2-4F43-9AFC-920D8C34282E@unixconn.com><51D42107.1050107@digsys.bg><2EF46A8C-6908-4160-BF99-EC610B3EA771@alumni.chalmers.se><51D437E2.4060101@digsys.bg><E5CCC8F551CA4627A3C7376AD63A83CC@multiplay.co.uk><CBCA1716-A3EC-4E3B-AE0A-3C8028F6AACF@alumni.chalmers.se><20130704000405.GA75529@icarus.home.lan><C8C696C0-2963-4868-8BB8-6987B47C3460@alumni.chalmers.se><20130704171637.GA94539@icarus.home.lan><2A261BEA-4452-4F6A-8EFB-90A54D79CBB9@alumni.chalmers.se><20130704191203.GA95642@icarus.home.lan><43015E9015084CA6BAC6978F39D22E8B@multiplay.co.uk> <CAOjFWZ4obK1cSmvTpW%2Bt4xKdMf%2BkJV5w-sujDT1AZoepj%2B5YrA@mail.gmail.com> <3CFB4564D8EB4A6A9BCE2AFCC5B6E400@multiplay.co.uk>
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On 05.07.13 02:28, Steven Hartland wrote: > > > If anyone wants my current patches which add switch to 4k ashift by > default > as a sysctl + works with QUIRKS too, just let me know. > > They are well tested, just we want more options before putting in the > tree. Is it not easier to add this as an option to zpool create, instead of an sysctl? That is, I believe we have two scenarios here: 1. Having an sysctl that instructs ZFS to look at the FreeBSD quirks to decide what the ashift should be, instead of only querying the 'sectorsize' property of the storage. I believe we might not even need an sysctl here, just make it default to obey the quirks --- but sysctl for the interim period will not hurt (with the proper default). 2. Have an option to zpool create and zpool add, that specifies the ashift value. Here my thinking is that it should let you specify an ashift equal or larger than the computed one, which is based on the largest sector size of all devices in a vdev. Don't know, but always wondered.. how hard is it to change the ashift value on the fly? Does it impact reads of data already on the vdev, or does it impact only writes? If only writes, it should be trivial, really.... Daniel
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