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=-5.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 E7DADC43461 for ; Wed, 2 Sep 2020 23:07:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D09B120767 for ; Wed, 2 Sep 2020 23:07:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726377AbgIBXHS (ORCPT ); Wed, 2 Sep 2020 19:07:18 -0400 Received: from mail-pg1-f173.google.com ([209.85.215.173]:45648 "EHLO mail-pg1-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726247AbgIBXHR (ORCPT ); Wed, 2 Sep 2020 19:07:17 -0400 Received: by mail-pg1-f173.google.com with SMTP id 67so491043pgd.12; Wed, 02 Sep 2020 16:07:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:autocrypt:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=e7FwOEGGEMeAosXGf3vEt7w+keSrNJPAi/ExRrKOBCU=; b=V4k7+7jchMBPctxWlfKyhAvuidJiYqetIm9pvUiyEgG23v35aQrxzCsSEXW90p4e2I kogls7hYKKvEOmQm5zGyJVQKA6PJyavt4iiV7l/SvWu5xaNtQdoxnMgPgPWcw6XgWrgm 5Iz5X/96hHBqOV/tKxwFRxYJvXf9MfVq4pHrqo6Xy0XbYQrZnvgZjLpwai92hbqVrhGX BLVxMOfZB68DlZgrMzmFBsAgkBMuulp0sDTlThC5HL5Kl9FGVg/b8AxCrzBlc6Nhk/M/ sNayhplD6geywI6Uot6BwAa2S7n+lm3jrfRngluGnBThBak21WSDtGijYsd57Yhx8X/Q +njQ== X-Gm-Message-State: AOAM530GL6ERgfYDjsIyuiblgnybQ1iV42rO0yuOzwqS/P/RjOthWUTH dVICM722I3//fngeeeHYbqG9zSIDTXA= X-Google-Smtp-Source: ABdhPJyNwqqk28YnUTSFsctPyYFjKwEJKzMtf3chE0SL+h36TuVZa5+3fkDIsos2ZSLZtqwzZAjlWA== X-Received: by 2002:a17:902:bcc2:: with SMTP id o2mr604619pls.87.1599088036436; Wed, 02 Sep 2020 16:07:16 -0700 (PDT) Received: from ?IPv6:2601:647:4000:d7:56b7:d2c3:23c8:7358? ([2601:647:4000:d7:56b7:d2c3:23c8:7358]) by smtp.gmail.com with ESMTPSA id u15sm437742pjx.50.2020.09.02.16.07.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 02 Sep 2020 16:07:15 -0700 (PDT) Subject: Re: [RFC] Reliable Multicast on top of RTRS To: Danil Kipnis , linux-rdma@vger.kernel.org, linux-block@vger.kernel.org References: From: Bart Van Assche Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata= mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e Message-ID: <3b2f6267-e7a0-4266-867d-b0109d5a7cb4@acm.org> Date: Wed, 2 Sep 2020 16:07:13 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2020-09-02 01:04, Danil Kipnis wrote: > RTRS allows for reliable transmission of sg lists between two hosts > over rdma. It is optimised for block io. One can implement a client > and a server module on top of RTRS which would allow for reliable > transmission to a group of hosts. > > In the networking world this is called reliable multicast. I think one > can say that reliable multicast is an equivalent to what is called > "mirror" in the storage world. There is something called XoR network > coding which seems to be an equivalent of raid5. There is also Reed > Solomon network coding. > > Having a reliable multicast with coding rdma-based transport layer > would allow for very flexible and scalable designs of distributed > replication solutions based on different in-kernel transport, block > and replication drivers. > > What do you think? How will the resulting software differ from DRBD (other than that it uses RDMA)? How will it be guaranteed that the resulting software does not suffer from the problems that have been solved by the introduction of the DRBD activity log (https://www.linbit.com/drbd-user-guide/users-guide-drbd-8-4/#s-activity-log)? Thanks, Bart.