From owner-freebsd-fs@freebsd.org Sat Jan 19 20:01:02 2019 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A8C201491337 for ; Sat, 19 Jan 2019 20:01:02 +0000 (UTC) (envelope-from jdelisle@gmail.com) Received: from mail-lj1-x244.google.com (mail-lj1-x244.google.com [IPv6:2a00:1450:4864:20::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 562766BB3F for ; Sat, 19 Jan 2019 20:01:01 +0000 (UTC) (envelope-from jdelisle@gmail.com) Received: by mail-lj1-x244.google.com with SMTP id t18-v6so14407773ljd.4 for ; Sat, 19 Jan 2019 12:01:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Jna/kS4geQAbTPeWI185voZL2QDEtV/29QBWxRd/7iA=; b=UHS/tKKovnmq3ytI7+2hzLw28HoeMG2Wodn0MiwOTSiRrdLTDkRIJzTi4MqFTz/To3 0HhXGVH7XruK34ppHWNiVF93VSiYq/Aidds+2WSpdtkQflJKxRzdUZR9/04lD4QbM53H uxkZsQxhdhPGNoWHvUksSvVvSKsOTkD/OM8eVT9c0xBbm8MTa2aF1UdttwcscFNufqIM cbuq7TfS0e2tLWRRNeJUyRETOYVTZ+8ClXFfZYJnmOihaQDTTkrUOSYXKxm2SVngLyGa KcyrwPeD8ROD3D1zvR+1uj7+oWFnUHZ3xI7CjzqnKUEthvnA5F5EM+e9nvUgJ1esqXe9 Po3Q== 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=Jna/kS4geQAbTPeWI185voZL2QDEtV/29QBWxRd/7iA=; b=qF8Gu56g4NWf1ILP8WYdyRdsoa1ulCinFFHv8b8DCoJA0OTqr00EqUbZyVgbTdtLon RlN6Fgv2jxLrDN8c7SPve1TifzOiiYJDbnx5frgEPqWOYFS/DhnHF/WylFcTtzk0tlLz mJnzs7N3owBoe+Vhe7HnfkvqZ4AW79NnaBXD+l3bBnqGevxgblyXGD7e0p6el/BCrNp0 NVxn4I2dPjHdRM7t0rnDWk/jP1/KNiYNqSDI7uijWD3kHKcpxPrCHne7CIiK9n3F5YHq OpIdY5CGjEDm2QF8uPhCVrmvL2rmcqhfkhzXG56BVdphg8udshjE/2xTb+Uo+fNjzAEY QrpA== X-Gm-Message-State: AJcUukd3I93ZkGdHjX0i/mSQ8VXaEa6i7SUF5kdTUX9xIgvLAliimQMv iiZS/dQon0/unyolPpcLm9Hy+3cMzskPfBvdGx0= X-Google-Smtp-Source: ALg8bN6UtyFIIe/A+kFsy1KlogSsQAcEAAEO/5Xj+3LBskSAl/ySBrR0lrWPk9zpMHHucbhZFd0T1N8VxujVr0heH60= X-Received: by 2002:a2e:1b47:: with SMTP id b68-v6mr12902545ljb.104.1547928059724; Sat, 19 Jan 2019 12:00:59 -0800 (PST) MIME-Version: 1.0 References: <1180280695.63420.1547910313494.JavaMail.zimbra@gausus.net> <92646202.63422.1547910433715.JavaMail.zimbra@gausus.net> In-Reply-To: From: jdelisle Date: Sat, 19 Jan 2019 14:00:47 -0600 Message-ID: Subject: Re: ZFS on Hardware RAID To: Ira Cooper Cc: Maciej Jan Broniarz , freebsd-fs@freebsd.org X-Rspamd-Queue-Id: 562766BB3F X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=gmail.com header.s=20161025 header.b=UHS/tKKo; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (mx1.freebsd.org: domain of jdelisle@gmail.com designates 2a00:1450:4864:20::244 as permitted sender) smtp.mailfrom=jdelisle@gmail.com X-Spamd-Result: default: False [-3.45 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[gmail.com:s=20161025]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[3]; R_SPF_ALLOW(-0.20)[+ip6:2a00:1450:4000::/36]; FREEMAIL_FROM(0.00)[gmail.com]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-fs@freebsd.org]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; DKIM_TRACE(0.00)[gmail.com:+]; MX_GOOD(-0.01)[cached: alt3.gmail-smtp-in.l.google.com]; DMARC_POLICY_ALLOW(-0.50)[gmail.com,none]; RCVD_IN_DNSWL_NONE(0.00)[4.4.2.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.5.4.1.0.0.a.2.list.dnswl.org : 127.0.5.0]; RCVD_TLS_LAST(0.00)[]; NEURAL_HAM_SHORT(-0.13)[-0.134,0]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+,1:+]; FREEMAIL_ENVFROM(0.00)[gmail.com]; ASN(0.00)[asn:15169, ipnet:2a00:1450::/32, country:US]; RCVD_COUNT_TWO(0.00)[2]; IP_SCORE(-0.30)[ip: (2.50), ipnet: 2a00:1450::/32(-2.11), asn: 15169(-1.83), country: US(-0.08)]; DWL_DNSWL_NONE(0.00)[gmail.com.dwl.dnswl.org : 127.0.5.0] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 19 Jan 2019 20:01:03 -0000 Wouldn't a write-back cache (battery-backed) improve write performance? Assuming the cache is sufficiently sized for the workload, would it not have an effect similar to ZIL, meaning low-latency persisted writes? On Sat, Jan 19, 2019 at 1:41 PM Ira Cooper wrote: > On Sat, Jan 19, 2019 at 11:43 AM Maciej Jan Broniarz > wrote: > > > Hi, > > > > I want to use ZFS on a hardware-raid array. I have no option of making it > > JBOD. I know it is best to use ZFS on JBOD, but > > that possible in that particular case. My question is - how bad of an > idea > > is it. I have read very different opinions on that subject, but none of > > them seems conclusive. > > > > Any comments and especially case studies are most welcome. > > All best, > > > > I've actually built Illumos based ZFS NAS systems based on raid controllers > and non-raid controllers. > > If given the choice, I'd use non-raid controllers, today. (HBAs) > > Why? Because ZFS handles the "raid" layer well. The write back cache a > RAID controller provides, isn't really needed with ZIL, nor desired. > > All a raid controller really brings in my experience is added operational > complexity once you use good enough hardware, mainly good ZIL drives and > HBAs. > > So it isn't really a "bad" idea, more just redundant, expensive and > inconvenient. You could have good reasons to do it, like that the RAID > controller is built into the motherboard etc. > > Just make sure your data integrity is #1. Writeback caches are properly > battery protected, or not used. etc. > > Best, > > -Ira > _______________________________________________ > freebsd-fs@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" >