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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 5D5EFC742D7 for ; Sat, 13 Jul 2019 09:22:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE0A62083B for ; Sat, 13 Jul 2019 09:22:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=protonmail.ch header.i=@protonmail.ch header.b="oKN8ZgEk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726548AbfGMJWY (ORCPT ); Sat, 13 Jul 2019 05:22:24 -0400 Received: from mail-40135.protonmail.ch ([185.70.40.135]:34673 "EHLO mail-40135.protonmail.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726448AbfGMJWY (ORCPT ); Sat, 13 Jul 2019 05:22:24 -0400 Date: Sat, 13 Jul 2019 09:22:20 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.ch; s=default; t=1563009741; bh=oHqMzhhNBnvM3cse/wSobfL4WH5VV6YqeT06eSmQYnU=; h=Date:To:From:Reply-To:Subject:Feedback-ID:From; b=oKN8ZgEkkqB/kv7mHNBNeUPCmD9AmG1M6VyLyE+8EMXcKIoS8dd27dKTr+YCOYdMZ n1FJEOLN4U27J4oloUMJCwhaqxjrj2ZY7EyGlJWHF4iwHT6SO4AnnR+hETDGh+dYD7 HH9S64BPPYhYVyvS5/f4YhoOBpq0xymGNzNWinJ0= To: "linux-btrfs@vger.kernel.org" From: "R. Schwartz" Reply-To: "R. Schwartz" Subject: Should nossd mount option be used for an HDD detected as non-rotational? Message-ID: Feedback-ID: bkDgnfjh8MsvyLj2Q6gYH7gJ_xhppUEW_38zMFhjHmQZrcjU44FunpgrBpP4HWGGznCn-ZE7GYZHi1bYU3WRNA==:Ext:ProtonMail MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org My HDD (one partition, BTRFS) reports itself as non-rational: $ cat /sys/class/block/sda/queue/rotational 0 According to btrfs(5), by default, BTRFS detects this value and turns on SSD optimizations for the HDD. Naturally, I'm puzzled... My question is: should I use the nossd mount option for the HDD? Following is more details about this HDD. It's a recent Western Digital Blue 2TB HDD, model WD20EZAZ. Given its cache size is a rather large 256MB, some people say it's likely an SMR (shingled magnetic record) HDD. Since Host-Managed and Host-Aware SMR HDDs support the `REPORT_ZONES` ATA/SCSI command, I ran this test using `sg3_utils`: # sg_rep_zones -R /dev/sda Report zones command not supported sg_rep_zones failed: Illegal request, Invalid opcode Therefore, _if_ it's SMR, it must be Drive-Managed SMR. So is there a good reason why the HDD reports itself as non-rotational? Does it have to do with SMR? Additioanlly, the HDD is connected through a SATA to USB connector. I original suspected it was an issue with the connector, but I tested with other HDDs with the same connector and they all report as rotational.