From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id DADC5C76190 for ; Thu, 25 Jul 2019 23:41:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F150229F9 for ; Thu, 25 Jul 2019 23:41:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=gmx.net header.i=@gmx.net header.b="ZOypsc5k" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727589AbfGYXl4 (ORCPT ); Thu, 25 Jul 2019 19:41:56 -0400 Received: from mout.gmx.net ([212.227.17.22]:53393 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727037AbfGYXlz (ORCPT ); Thu, 25 Jul 2019 19:41:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1564098106; bh=5DrjjJ0Qy2J/HhvNGL2HDoD4BbCh+h3pWiCuY6TRXyU=; h=X-UI-Sender-Class:Subject:To:References:From:Date:In-Reply-To; b=ZOypsc5k2OY0aToa52ZSkapWoy1ct0fBvWnMFl+Tq0oLEuCbxwdciFBWtuKRUkr61 kCXOvrMlYcG1H3Az8fWE+/Y8oNxNF7JvJOut1ln0YMC3RtMCoZtJ7AjBFSnSHYhBbn uE04A7RvIFXV1WwFbynbmUfjbLIsk/e6VKIFZCso= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([54.250.245.166]) by mail.gmx.com (mrgmx103 [212.227.17.174]) with ESMTPSA (Nemesis) id 0Mdrph-1i3D2i4C5N-00Pff9; Fri, 26 Jul 2019 01:41:46 +0200 Subject: Re: [PATCH] btrfs: Allow more disks missing for RAID10 To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org References: <20190718062749.11276-1-wqu@suse.com> <20190725183741.GX2868@twin.jikos.cz> From: Qu Wenruo Openpgp: preference=signencrypt Autocrypt: addr=quwenruo.btrfs@gmx.com; prefer-encrypt=mutual; keydata= mQENBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAG0IlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT6JAVQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWCnQUJCWYC bgAKCRDCPZHzoSX+qAR8B/94VAsSNygx1C6dhb1u1Wp1Jr/lfO7QIOK/nf1PF0VpYjTQ2au8 ihf/RApTna31sVjBx3jzlmpy+lDoPdXwbI3Czx1PwDbdhAAjdRbvBmwM6cUWyqD+zjVm4RTG rFTPi3E7828YJ71Vpda2qghOYdnC45xCcjmHh8FwReLzsV2A6FtXsvd87bq6Iw2axOHVUax2 FGSbardMsHrya1dC2jF2R6n0uxaIc1bWGweYsq0LXvLcvjWH+zDgzYCUB0cfb+6Ib/ipSCYp 3i8BevMsTs62MOBmKz7til6Zdz0kkqDdSNOq8LgWGLOwUTqBh71+lqN2XBpTDu1eLZaNbxSI ilaVuQENBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAGJATwEGAEIACYWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCWdWBrwIbDAUJA8JnAAAK CRDCPZHzoSX+qA3xB/4zS8zYh3Cbm3FllKz7+RKBw/ETBibFSKedQkbJzRlZhBc+XRwF61mi f0SXSdqKMbM1a98fEg8H5kV6GTo62BzvynVrf/FyT+zWbIVEuuZttMk2gWLIvbmWNyrQnzPl mnjK4AEvZGIt1pk+3+N/CMEfAZH5Aqnp0PaoytRZ/1vtMXNgMxlfNnb96giC3KMR6U0E+siA 4V7biIoyNoaN33t8m5FwEwd2FQDG9dAXWhG13zcm9gnk63BN3wyCQR+X5+jsfBaS4dvNzvQv h8Uq/YGjCoV1ofKYh3WKMY8avjq25nlrhzD/Nto9jHp8niwr21K//pXVA81R2qaXqGbql+zo Message-ID: Date: Fri, 26 Jul 2019 07:41:41 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190725183741.GX2868@twin.jikos.cz> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="p2Pn2ByTKKkOVc1wnYArLAeroBLrAV6hH" X-Provags-ID: V03:K1:KGmuvniE1rrba9kSNLW6QTS92/ALNU9NP2Wk/ZOwCagrJOLr5Q3 WU4HShrIfFm4WZVsrCPnRHRBOvNkfHc2GFwESfAgVNPGPGybhsI89dJxQWvr2olCngGapWw xYEkMcqKTwnOWxdEZM+CEXDxaFKXwKa0EpiYy8iyH1WsYB6LZXKWjnlfZnrzUJK+hxuuWdH AhdE6KSMwuGxuiGYXJXZw== X-UI-Out-Filterresults: notjunk:1;V03:K0:TUvRir+A0C4=:HSzCTOfaXxlBLuVGkoV0/v h1OKnR3PhYyLhbbBVFTcQC+/H/nyxEN0GTgfFzYzm0PzPKIHHq8LifZIrrkMhxfsrxcSYgvHf fLUmA5DrCCu6rRkJ9sRclb9ndycZkxeZo9sEYaMUoYiVdo8WTKf7d3QSQ4vcuBjujAB+mUeEO z3DmoZWUGhK3BuSzqHdx8Y0uko5SpVsE+D+haKqsSWF2NPTvCTRU/AQKBXTdkEdtjLT02MpY/ vR46+Ildx6ezg3chDEf5lILlQlXilJa633+sAuUUWqd2BYNWxmwjOoscT5ZdEh55AQiqVudc3 VHjZMei4Pw3avaXLzkKAU7746y245laB9NH8dksbyKfPaj8jNotmcZosr930megrkYetw2kK1 gdS2lwr5EsJX7rtg3T6oQmucG592MOv6ZxmtXf1fSnYohlqINDay6Rc9eGx845xZqjeZqqIT/ GkQt5PHWy08mVmf4nUeUOZPcvTZ5Oi6DypPSECAsJ1ELYe1klY4YjgZVNn3tE9QJGGONz6T08 wV2IKlQnqNleoirtlJQ9Uqp59Emo6Tljf3/b+8uD0AmLBqbAo8gvuTYCMYZtBi4I0OCa4pWLU 7mxhZL6+JBQ1BSndoWuGHkZ8ayNrV2C0f4Ll12sdXT/1YyDd79e0NQdexNrbBhIo/h3tOBr2x KV43dITunqr0fxo3yek4EL0+BB3rRRRHDV+BRw8YMZwVNi9XR81yOJ+QlBYFe+NWYcJtDJzCX TaBuLgGOAx55QZFd8MZG/S0YHkWmenrhAKd5HyQKBz8NcH8hImSJZkGO4nuxlFVQYo9uK5inL S3U/MYLi7Lg4wALzKHr4Oxi/9gIWDNvSc7k1MKYBqn8s98by5VISTR8uDBxvE5Sz5Pg170KbS X9T72Kle6NIJTDJLP3glA+/MTnr8xH/IBjOzEk5OFVT6KLxbttm/owE+jN+mwNIA5pjgD6p+g 4eR8STKxjyDtgDWAxwvQZrm64WWGBujJtgoeCmMaRsw7ThSUHAeW6pqPaD9M7BAXYcKaNLmKK A8DEHFvrASGVnI+UW339nT2B4ahV/yRzVIuUbwgWKJ5GvLKMgUWNugCFKPEk/W0QN1pQ/w8r0 EkTWYjINWzGC9g= Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --p2Pn2ByTKKkOVc1wnYArLAeroBLrAV6hH Content-Type: multipart/mixed; boundary="45u8ylyl9zsDeXCHqwBi3upPAlF3DsTnS"; protected-headers="v1" From: Qu Wenruo To: dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org Message-ID: Subject: Re: [PATCH] btrfs: Allow more disks missing for RAID10 References: <20190718062749.11276-1-wqu@suse.com> <20190725183741.GX2868@twin.jikos.cz> In-Reply-To: <20190725183741.GX2868@twin.jikos.cz> --45u8ylyl9zsDeXCHqwBi3upPAlF3DsTnS Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2019/7/26 =E4=B8=8A=E5=8D=882:37, David Sterba wrote: > On Thu, Jul 18, 2019 at 02:27:49PM +0800, Qu Wenruo wrote: >> RAID10 can accept as much as half of its disks to be missing, as long = as >> each sub stripe still has a good mirror. >=20 > Can you please make a test case for that? Fstests one or btrfs-progs one? >=20 > I think the number of devices that can be lost can be higher than a hal= f > in some extreme cases: one device has copies of all stripes, 2nd copy > can be scattered randomly on the other devices, but that's highly > unlikely to happen. >=20 > On average it's same as raid1, but the more exact check can potentially= > utilize the stripe layout. >=20 That will be at extent level, to me it's an internal level violation, far from what we want to improve. So not that worthy. Thanks, Qu --45u8ylyl9zsDeXCHqwBi3upPAlF3DsTnS-- --p2Pn2ByTKKkOVc1wnYArLAeroBLrAV6hH Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEELd9y5aWlW6idqkLhwj2R86El/qgFAl06PjUACgkQwj2R86El /qhplwgAi0LSjDWKnUvxVE/TQqcQQgENmhbHjsWaYKEqS00/N1sVEAIxsHzU8H0Z iO8e6pU752BVXNTafmlok+yUj4qQG2bY7rPbzuK1MOGxEH073L2ivQBLOAiR5Tgw fh67en93zgbz0lIlDHFnw/3lZd8FTMUjvrvyzAUXc5BfE40yPHlBEVD3fh49vlsu keNbnlBQsjwl3gOCdHndHDFjxCS2p3TI2J6ApIsUtanOTVWNMV28NmBTz9Ws5/kN HdCVACyVbFeSqW6sQ4G5m2bqvVWogzhGHkWtqphm6JyIOsBv7/M4+2U4fmc6q04R MnMbCqnYpqHJ289MayX0fScme/fwAA== =4uL/ -----END PGP SIGNATURE----- --p2Pn2ByTKKkOVc1wnYArLAeroBLrAV6hH--