From owner-freebsd-fs@freebsd.org Thu May 6 15:19:22 2021 Return-Path: Delivered-To: freebsd-fs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 684CF624E6D for ; Thu, 6 May 2021 15:19:22 +0000 (UTC) (envelope-from asomers@gmail.com) Received: from mailman.nyi.freebsd.org (mailman.nyi.freebsd.org [IPv6:2610:1c1:1:606c::50:13]) by mx1.freebsd.org (Postfix) with ESMTP id 4FbcgZ171Mz4mXR for ; Thu, 6 May 2021 15:19:22 +0000 (UTC) (envelope-from asomers@gmail.com) Received: by mailman.nyi.freebsd.org (Postfix) id 267D5624D7B; Thu, 6 May 2021 15:19:22 +0000 (UTC) Delivered-To: fs@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 263E5624D7A for ; Thu, 6 May 2021 15:19:22 +0000 (UTC) (envelope-from asomers@gmail.com) Received: from mail-oo1-f44.google.com (mail-oo1-f44.google.com [209.85.161.44]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (2048 bits) client-digest SHA256) (Client CN "smtp.gmail.com", Issuer "GTS CA 1O1" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4FbcgZ0YG7z4mVp for ; Thu, 6 May 2021 15:19:21 +0000 (UTC) (envelope-from asomers@gmail.com) Received: by mail-oo1-f44.google.com with SMTP id c6-20020a4aacc60000b02901e6260b12e2so1316551oon.3 for ; Thu, 06 May 2021 08:19:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=SipB3WoNN29rdus1UhBUalZlNJs9myXkem8hT81/6FQ=; b=AbHqSRAcdkfvL+55keuVYQmxtcEdlkzA8MUY+ulBGLTfd2D5bM7npJbPi0GrivQ1kv yKPRoZl9maCG15I8utoK8PNfL2sUJkgxYx+DvmHJycM7F/dex9r9+2ZWPeWUKAXvkhml oX4xgmYFhl3kXhQUc66w8vDk5uH40qsBJ0Q5E2kbJ/+i/nytKa6nUUQeTJouF7mXVq6L SuHUnYhC8Ona7KK1yZZb4F+XQfj3L+H07/w9TYBKfkqdJ6f0LTh0swxg5gJeA1Qj2jdW sQumtMfTWM9yjwBg+yhMe2CKWgKlMBPBKdsLX++ZTbssfJR8Np0pLfJ0C2jw/zj0C2+2 Zxeg== X-Gm-Message-State: AOAM532CNeNZhS81HhXscBpBeXHSYa9xZC8ehx3oGh6/6zyH7Ybi+19x Dhuh0l02pP3KOBvCHRDP21KALLCxl05NHvniu8E= X-Google-Smtp-Source: ABdhPJyddxSt4r1oNtNs2a+CiRAOq0K/knJMzN+RnpLD8X7eMjmEBG7+hUFUfJAqZJ/F3oNEWVKqmjKx6hw4aeVs1Ng= X-Received: by 2002:a4a:8dd6:: with SMTP id a22mr3923623ool.74.1620314360113; Thu, 06 May 2021 08:19:20 -0700 (PDT) MIME-Version: 1.0 References: <578487FF-1D89-4A9E-AD97-6B5DCD9F785A@gmx.com> <62B46E11-A40C-4119-8525-20E3F3539D61@gmx.com> In-Reply-To: From: Alan Somers Date: Thu, 6 May 2021 09:19:09 -0600 Message-ID: Subject: Re: Dual-port SAS HDD ? To: Ben RUBSON Cc: "fs@freebsd.org" X-Rspamd-Queue-Id: 4FbcgZ0YG7z4mVp X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.34 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 06 May 2021 15:19:22 -0000 On Thu, May 6, 2021 at 9:14 AM Ben RUBSON wrote: > > > > On 6 May 2021, at 15:51, Alan Somers wrote: > > > > On Thu, May 6, 2021 at 7:37 AM Ben RUBSON ben.rubson@gmx.com>> wrote: > > > On 6 May 2021, at 15:24, Alan Somers asomers@freebsd.org>> wrote: > > > > > > On Thu, May 6, 2021 at 4:52 AM Ben RUBSON ben.rubson@gmx.com> >> > wrote: > > > Hi, > > > > > > I'm building a new ZFS pool from scratch, choosing my own hardware > etc... > > > For sure I'll go for the standard SAS2008 / SAS3008 controller. > > > > > > However, I'm wondering whether or not I should absolutely go for > dual-port SAS HDD (with dual backplane, controller...). > > > I have some difficulties to find enterprise grade dual port SAS HDD. > > > HGST used to provide Ultrastar SAS HDD which were dual-port. > > > However, strangely, Western Digital does not advertise their Ultrastar > DC SAS HDD as bringing dual-port, so I guess they're not. > > > > > > Any thoughts / advices regarding this topic ? > > > > > > Many thanks for your help, > > > > > > Kind regards, > > > > > > Ben > > > > > > It's just a matter of high availability. Can you tolerate an outage > if a JBOD I/O controller fails? If so, then you don't need dual-port. But > server crashes are more common than JBOD I/O controller failures. So you > should worry more about that. > > > > Thank you Alan. > > Of course you're right, JBOD IO controller is not the first outage > cause, and disks themselves are more prone to fail... > > > > I even wonder whether or not dual path is actively used for HDDs, as > dual-port ones are rather hard to find... > > Not sure then it's really worth it... > > > > Of course feel free if I'm wrong / I missed something / one actively > uses it and has some experience / references to share ! > > > > Thank you again, > > > > Ben > > > > Sure, dual paths are actively used. They work well with gmultipath, > which is how I use them. And AFAIK all SAS drives are dual-ported. > Western Digital describes their drives as "dual port" on this site: > > > https://www.westerndigital.com/products/data-center-platforms/ultrastar-sas-series-ssd > < > https://www.westerndigital.com/products/data-center-platforms/ultrastar-sas-series-ssd > > > You're right, SAS SSDs are dual-port. > However, their SAS HDDs are not advertised as such : > > https://www.westerndigital.com/products/data-center-platforms/ultrastar-dc-hc600-series-hdd > > https://www.westerndigital.com/products/data-center-platforms/ultrastar-dc-hc500-series-hdd > So I wonder. > > Ben > Oh, good point. I don't know. You could always ask. I use mostly Seagate dual-ported HDDs. -Alan