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=-2.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 3F6A0C07E9A for ; Wed, 14 Jul 2021 13:02:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1DDAA61154 for ; Wed, 14 Jul 2021 13:02:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239344AbhGNNFD (ORCPT ); Wed, 14 Jul 2021 09:05:03 -0400 Received: from mout.gmx.net ([212.227.17.20]:46505 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231391AbhGNNFD (ORCPT ); Wed, 14 Jul 2021 09:05:03 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1626267727; bh=61wToHsiFCNgQHboLxtx9jaxZ8VOVvkHSyUVnzHEp18=; h=X-UI-Sender-Class:Subject:To:Cc:References:From:Date:In-Reply-To; b=Ka+T8MnaOG2KkNxpX051Cv7ThzLf/Ja4mjymr4vJgA9D6p/cuprqJNJWNaM617E3F I0UcYi7cbKu1ytmb/BzUXCpycK/SlHCPFtLNRJqw4YyYf4SD+MXcGemmMmamwOUG1F P+EgE8+4vjvAHl0D/rqrYmpUq5nXr5BGTAeXyNok= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [0.0.0.0] ([45.77.180.217]) by mail.gmx.net (mrgmx105 [212.227.17.174]) with ESMTPSA (Nemesis) id 1MlNp7-1lITPX1jvp-00llrp; Wed, 14 Jul 2021 15:02:07 +0200 Subject: Re: Enhancement Idea - Optional PGO+LTO build for btrfs-progs To: Neal Gompa , DanglingPointer Cc: Btrfs BTRFS , Damien Le Moal References: <2a29adba-8451-7550-a6f1-835be431953b@gmx.com> <762a5060-e38d-ccef-293d-c05389d5b0af@gmail.com> From: Qu Wenruo Message-ID: Date: Wed, 14 Jul 2021 21:01:59 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:HueKPWI1LZGZCVXPzoNPSaD792GhIlJv3h2L26jKx9oLZwH4wjk USI84dTXSbit5msWLB+ybwIaybPTnT+9Q+e34M14apiwKnqYxo97jGNtS6X8LaDivY40Sef qWGItlqdQNdl7WV/qYIpQINpYCy0rxcmzi7heZvxLGpuDq7Zkuoq6Huhg6rXNt67dN7f8Mi F7J3Y0JLhpt24nKsV4jsg== X-UI-Out-Filterresults: notjunk:1;V03:K0:HSN5nRPmz3E=:OY0E90JicFM6EqtIcSAlQ6 QwJRjQElFkaOifbiew5ExQRUL8kdTkE1n7nBebD67yoQKg5PxDM61uWZhsKy3sjzmBCskstGI Zi1lBT9GnqsMlQpbPZ1Enbkk8nrWkjeLmP49Wr2N3AdA7InWRCKyYirndhZjdGv3/lPUco7T+ GvJBjS/MQJNFvBPkmpB73ilphxu3U5dSwul0i4JPVAP5cNHqv1N2Uuy1uNAXGDZbxKcjKZi0N apabQZoswHq4VjcNiIC4//Cue50rJu3FZMCw8so2WCuGHRbdvoRFH566Oq3B7fjcyqEm6crJ/ GbznqHkxcVFFOdS7Rnie3PIaCClypgUWdwMJzxlceGRHV1mB8pK9gPt7eE5v0sssmqt5KBO+N zQb5A4nZPLlO3TNR5YBYg79K83Clvnd/ielhPwpdVpCE9jIbh9F9cMlNTBNKnZp8MoLmsOpL1 R/DjyilMnvv/qrjFOXyJrz02TQsnvDa1nWJ6p1MJGjZBk830aHZ6n/X7aOX9KhMcb/xjvMUL/ HdExSeiVZSbfnPQDpOFpswHpmYb2+AEg54hAFqf95dtTwmZoHTKu1+wyYu1fi+K+otjHi9rlc BFidJyr4W4GUQi0GOcT2To3YyAN4UCze1Mp4tk9vjDslfgLIUNbxniX5QYgEFY/ptneS4gK7F q6mgOjpVqKku8RWAP4DzNYZaojVdev1TImXyw/OK4vh1ObHUrl0D+Oioe1ohNfdZNF7iO9cDk P5O5V62IrMBx1HCrLWDjz4lpu+hQ1toJ9EhryUn2Uml8ehOBL4y6BtXU9uQYdVckshoX+JF8a XORj7j84PCV8kWLpw4z877iCXKV9zIfSgWA290+q+EwqeQ1jymXHIFN+1xYq1LcaqWKr0mJwX W/tfdwIUSsv3sWGSS2saauMGaqlt1Vh0pR0etv0sQ8CxXIHWkMNkSp6sYkU7QUKS+25Qz2qu1 HDgXKp+Y7pguF0D28qv88X/ZcbYO+bg+6QNDdNAYpNWraR+3o9dwemln9m+/QnXCAIMr16ql0 MLdn5ZTROWVdsX6BJjglBy3IUWh/lzjovYNm2Nmsl4K6XKIremGwiEQhWxikVCkMAwqgJE336 h1qJlRTNrie+Qg+vwI9twHc9JsQUbmpNKiXZ32xlq+dS5DPhifxIn2IgA== Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 2021/7/14 =E4=B8=8B=E5=8D=888:35, Neal Gompa wrote: > On Wed, Jul 14, 2021 at 5:22 AM DanglingPointer > wrote: >> >> Yes noted. >> >> We're aware of the write hole risk. We have battery backup for both >> workstations and automation to shut it down in the event of power-outag= e. >> >> Also they are lab workstations. Not production. Data is backed up to >> two locations. >> >> The primary reason for RAID5 (or 6) is economics. Money goes way >> further with RAID5 compared to other RAIDs (1,/10,etc) for the amount o= f >> data store-able in an array with the reliability of being able to loose >> a disk. I'm sure there are thousands of others out there in a similar >> situation to me where economics are tight. >> >> Would be good if at some point RAID56 can be looked on and fixed and >> further optimised so it can be declared stable. Thousands of people >> would further flock to btrfs, especially small medium enterprises, orgs= , >> charities, home users, schools and labs. >> > > Btrfs RAID 5/6 code is being worked on[1], so this will be fixed > eventually. I personally look forward to this being resolved as > well... > > [1]: https://lore.kernel.org/linux-btrfs/BL0PR04MB65144CAE288491C3FC6B07= 57E7489@BL0PR04MB6514.namprd04.prod.outlook.com/ > From what I know, to solve the RAID5/6 write hole, the real solution will be a journal, just like what all other soft raid56 does. This means, we will have a new RAID5/6 profile other than the current non-journaled RAID5/6. Existing users still need to convert to the new profiles, not something will be fixed magically. Thanks, Qu