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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22D5AC54EAA for ; Fri, 27 Jan 2023 20:44:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232915AbjA0Uod (ORCPT ); Fri, 27 Jan 2023 15:44:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232616AbjA0Uob (ORCPT ); Fri, 27 Jan 2023 15:44:31 -0500 Received: from mail-pj1-f48.google.com (mail-pj1-f48.google.com [209.85.216.48]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E2D3E7E05F for ; Fri, 27 Jan 2023 12:44:03 -0800 (PST) Received: by mail-pj1-f48.google.com with SMTP id b10so5707112pjo.1 for ; Fri, 27 Jan 2023 12:44:03 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=52wpdKvl7nLqTMNq3a1fe6Tc4ELdw994Z1EKdlORxMw=; b=Y2wbe1xT9RVSTVB3QMOs21WEIfbmXFanilxxCpw1P1kdzJR1SH+pI528HNNZSyUGwB +uPVydyLWGtTiXAbb4xOrroM6UO7uoFxibBn0IZhf/qCcT062SKv6DJiVvzV6r/BgNm5 +K6h0sdoCHQVXrWRsrtLzHu160/JF1Vq7fAf8qWyKfs1PRm2192LdNLxq+BAYhIeN7+i lSRmeZ9nicOEU9rqFfqSekLoDFoRtNClcGuI8lFvPkWV9lUg/hFprE4m7S+na7INDJlk UvlKKratFGB4k+oYKWti1ufkq4G9tmG+hJ2kGpBlAWpyRTG/P/SjmRgpJ0hKKwvqSpxy 0W8A== X-Gm-Message-State: AO0yUKW/QLCyEgjnQN54pC3fW1VooiVyO3DkBbXW7Qe1+ieTansxQvbQ pFYy7WMT+Sq3rUVqJkwasqw= X-Google-Smtp-Source: AK7set8MhvieNBTCdIZBXtTk+2aXo/4hiqQRJ+6Ox4t+QnfH4uZ001EX0dngFo22A8a1Rznk3/OwSQ== X-Received: by 2002:a17:902:dacf:b0:196:15bc:e200 with SMTP id q15-20020a170902dacf00b0019615bce200mr16693804plx.4.1674852195599; Fri, 27 Jan 2023 12:43:15 -0800 (PST) Received: from ?IPV6:2620:15c:211:201:5051:6ed0:9022:37aa? ([2620:15c:211:201:5051:6ed0:9022:37aa]) by smtp.gmail.com with ESMTPSA id ix1-20020a170902f80100b001960e9dd05esm3282796plb.112.2023.01.27.12.43.13 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 27 Jan 2023 12:43:14 -0800 (PST) Message-ID: <65e11f62-0109-ee6f-0cd0-56ae30dd1208@acm.org> Date: Fri, 27 Jan 2023 12:43:12 -0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: The PQ=1 saga Content-Language: en-US To: Brian Bunker , linux-scsi@vger.kernel.org Cc: Martin Wilck , "Martin K. Petersen" , Christoph Hellwig , Hannes Reinecke References: <4f9794d2-00ed-22da-2b4b-e8afa424bf17@acm.org> <9545766a-298d-1358-46f0-64ccfaf30ca0@suse.de> <6A8AA317-32B0-48F4-82DC-82B65A221A9F@purestorage.com> From: Bart Van Assche In-Reply-To: <6A8AA317-32B0-48F4-82DC-82B65A221A9F@purestorage.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On 1/27/23 11:57, Brian Bunker wrote: > So the question becomes how should initial scan work when a LUN has a PQ=1 set. > It is a valid, by spec with ALUA state unavailable but doesn’t seem to be > handled. Why allow an sg device but not an sd one on initial scan in this case? There > are probably many ways to fix this. I think the simplest is to allow sd device creation > on LUNs were PQ=1, and only restrict PQ=3. I am not sure the side effect of this on other > targets. The other approach which will no longer work after the revert is to trigger a > rescan from the target. This is sub-optimal since it is disruptive. Any approach involving > the ALUA device handler will not help since there is no device to transition if it is > discovered with PQ=1. When Mike Christie and I looked into the ALUA unavailable state many years ago we concluded that using this state is so troublesome that it's better not to use this state. How about using active/optimized and active/non-optimized instead? Thanks, Bart.